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Smart hubs explained

Amazon Alexa vs Google Assistant, Siri and Bixby

By Tom Morgan

Article 2 of 3

In the battle of the voice assistants, which comes out top? We put Amazon Alexa, Google Assistant, Apple's Siri and Samsung's Bixby to the test.

Put us to the test

Our Test Labs compare features and prices on a range of products. Try Which? to unlock our reviews. You'll instantly be able to compare our test scores, so you can make sure you don't get stuck with a Don't Buy.

If you're shopping for a smart hub, your first buying decision is a big one - which voice assistant are you siding with? Below, you'll find details of how effectively each system manages your schedule, whether or not it can control your connected tech - and how good its sense of humour is when asked to tell a joke.

Smart home hubs continue to grow in popularity, which means the voice assistants powering them are getting smarter with every update. Even so, there are some key differences between the four key players - Amazon, Google, Apple and Samsung.

To see just how significant these differences are, and to find out if one was clearly better than the other, we conducted a test in the Which? office. We asked each assistant the same 13 questions and noted their responses to see which answered the most correctly and provided the most useful information. Take a look at the questions we asked or jump to a specific assistant to see if it excelled or struggled.

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Want to see which voice-activated smart hubs get the thumbs up in our tests? Head over to our smart home hub reviews.

Amazon Alexa 

Debuting inside the Amazon Echo, the Alexa voice assistant can be used to order goods straight from the Amazon website. It lives inside Amazon's range of smart hubs (Amazon Echo and Amazon Echo Dot) along with the retail giant's Fire tablets and TV streaming sticks.

If you buy an Alexa-enabled smart hub, the first step is to configure it using the free Alexa app for Android and iOS. From here, you can fill in some information about yourself to improve Alexa's responses. Tell it where you work, for example, and you can request traffic updates before you head out in the morning. The list of commands Alexa can process is huge - it can set alarms, control other smart devices, play music, sync with your Google Calendar events, read news headlines and act as an alarm clock.

One of the key features setting Alexa apart from its competitors is 'skills'. Simply put, these are third-party apps that you can download to make your Alexa-powered hub that little bit smarter. There are tens of thousands of skills to download, covering everything from bite-sized fitness workouts to music streaming and goal alerts for football matches. You can discover new ones inside the Amazon Alexa smartphone app.

You don't have to spend big to get yourself an Alexa-powered smart hub - the Amazon Echo Dot is £50. But make sure you read our full Amazon Echo Dot review before opening your wallet.

'Alexa, tell me a joke!'

What do you call a strawberry that uses foul language? Berry rude.

Where can I find Amazon Alexa?

Amazon EchoAmazon Fire Stick with Alexa Voice Remote, Amazon Fire TV with 4K, Echo Dot, Echo Plus, Echo Show, Echo Spot

How did it do in our test?

Alexa did very well, managing to answer 12 of the 13 questions. It was the only assistant that could add items to our shopping basket and, once we'd told it where we worked, it gave detailed information on our commute.

Good for

  • Third-party apps - tens of thousands of skills are available for download
  • Online shopping - ordering goods through Amazon.co.uk is a breeze
  • Suggesting new uses - the Alexa app has a 'Things to try' page with plenty of ideas

Not so good for

  • Mobile - the Alexa smartphone app can handle basic factual questions, but Google Assistant offers far more detail

Our verdict: An intelligent voice assistant that's perfectly suited to online shopping. Downloadable skills help you personalise your experience with apps for the services you use the most.

Google Assistant 

You can have a chat with Google Assistant through your smartphone or via one of Google's smart hubs. Backed by the world's biggest search engine, Google Assistant's major strength is answering questions in detail and running web searches.

To get the most out of a Google smart hub, you'll need to download the Google Home smartphone app. From the app, you can see which devices are connected to the smart hub. As with Alexa, you can also decide which music provider will be your default if you ask it to play a tune - Google Play Music and Spotify are the most popular options.

If you own other Google gadgets, you can control those with a voice command through Google Assistant. Plug a Google Chromecast into your TV and you can tell the artificial intelligence (AI) helper to turn on Netflix or YouTube and start playing your favourite show. If you've set up some Philips Hue lights in your living room, you can lower the brightness or change the colour without getting up off the sofa.

Google Assistant will come in handy if you already make use of Google services such as Gmail and Google Calendar. You can ask: 'OK, Google. What does my schedule look like for today?'. Sending text messages from Google Assistant on a smart hub is also an option provided you've given it permission to 'scan' your smartphone contacts.

Unlike Apple's Siri, Google Assistant copes effortlessly with follow-up questions. You can ask 'Who is David Attenborough?' and then ask 'How old is he?' straight after - the system will know who you're referring to.

'OK, Google, tell me a joke!'

A set of jump leads walk into a bar. The bartender says, 'I'll serve you, but don't start anything'.

Where can I find Google Assistant?

Chromecast, Chromecast Ultra, Google Home, Home Max, Home Mini

How did it do in our test?

Follow-up questions that don't make sense without the context of the preceding request are a tricky proposition for voice assistants. Our test showed that Google Assistant was the best at giving good responses to these sorts of questions. Overall though, it only managed to answer 10 questions, while Alexa managed 12. We thought Google Assistant would work well with Google's own services, but it couldn't add events to our Google calendar.

Good for

  • Detailed replies - no other voice assistant can top Google's for web searches
  • Multiple accounts - the Google Home can work out which family member is speaking and give search results and responses accordingly. Alexa has also been able to do this since October 2017
  • Controlling other products - interacting with Google Chromecast and smart lighting is a breeze

Not so good for

  • Shopping - Amazon is a major Google rival, so you can't order from the Amazon website through Google's smart hubs

Our verdict: Google Assistant is the leader of the pack when it comes to providing detailed responses to web searches. Alexa is better equipped when it comes to third-party apps, though.

Apple Siri 

Since its original release on the iPhone 4S back in 2011, Siri has arrived pre-installed on every iPhone. It's tucked inside a range of Apple laptops and iMacs, and the company's first smart speaker, the Apple HomePod.

You can summon Siri with a quick 'Hey, Siri'. The cheerful assistant can help you schedule events and set reminders. If you already use Apple apps frequently (Calendar, Notes, Reminders) Siri can interact with those apps without much trouble at all.

However, as one of the first major voice-activated assistants, Siri is starting to show its age. The helper is rather limited compared with Google Assistant and Alexa. For one, the HomePod doesn't have voice training enabled, so it won't adjust its responses based on which family member is speaking. You can only use voice commands for Apple-approved services, which means Spotify users are out of luck.

If you have Apple's HomeKit app set up, you can use Siri commands to control various internet-enabled gadgets. The Scenes feature lets you play with a group of products with one action. For example, you can create an 'I'm home' scene and configure it so that, when asked, Siri turns on your lights, your TV and your heating through your smart thermostat in one go.

The HomePod is Apple's first smart speaker. It's powered by Siri, which can play tracks from Apple Music and your iCloud Music Library. If privacy is a concern, it's worth noting that you can stop Siri from reading out texts and reminders to a paired iPhone. 

'Hey, Siri, tell me a joke!'

A sloth walks into a bar, waves to get the bartender's attention, and says, 'I'll have... a soda water'. The bartender says, 'Hey, why the long paws?'.

Where can I find Siri?

Apple HomePod, Apple iPhones, iPads and MacBook laptops

How did it do in our test?

Siri gave satisfactory answers to eight of our 13 questions. As with all the assistants it did well with certain requests, although it was the only one that couldn't play a radio station on request. It's not great for routes either. When we asked it to tell us how long it would take to get to work, it just did a Google search, which isn't very helpful. It integrates with the phone. Setting timers and calendar events adds them to the relevant app on your iPhone.

Good for

  • Scenes - you can control a selection of smart devices with a single voice command
  • Apple apps - if you already use Apple services, Siri can help you dig out information quickly and easily

Not so good for

  • Compatibility - Amazon Alexa and Google Assistant play nicely with third-party apps. Siri isn't as willing

Our verdict: Siri simply can't do as much as Amazon Alexa or Google Assistant. It's well-suited if you're fully invested in the Apple ecosystem, but its rivals are a step ahead.

Samsung Bixby 

Bixby is the new assistant on the block. It first appeared in Samsung Galaxy smartphones in 2017 and has since moved into TVs, too.

Galaxy handsets have a dedicated button to activate the speaker or you can say 'Bixby' to prompt the assistant to start listening. Some features differ depending what device you're using Bixby on. You can ask it to send texts, make calls and answer basic queries on smartphones. On TVs, Bixby can search for specific shows and movies, or you can ask to see content starring certain actors - you can search by genre, too.

Samsung has spent 2018 consolidating its SmartThings smart home control software. You can now use Bixby on your smartphone or 2018 Samsung TV to control a variety of devices, including smart light bulbs, thermostats and wireless security cameras.

All the other voice assistants have a head start on Bixby and it shows. They all resort to an internet search to answer trickier questions, but Bixby does it more often. We asked all of them to spell cardamom and while the others reeled it off, Bixby searched the internet and delivered a response from a website. We still got the right answer, but because Bixby is simply reciting from a website it can take longer to get to the pertinent information. It had a similar issue when we asked it how long it takes to boil an egg. While Alexa and Google Assistant gave us a succinct answer, Bixby once again read from a webpage. All the assistants look for answers online, but Bixby isn't as good at disguising it.

'Bixby, tell me a joke!'

How did Dorothy's smartphone get back to Kansas? It said, there's no place like home screen.

Where can I find Bixby?

2018 Samsung QLED, 8 Series and 7 Series TVs, Samsung Galaxy S8, S8+, S9, S9+, Note 8, A6 and A8.

How did it do in our tests?

Like Siri, Bixby also got eight points in our test. It has similar strengths and weaknesses too. Any commands that relate directly to something on the phone, such as setting timers and adding events to calendars work well. It was the weakest at understanding our commands though. When we asked it to play BBC Radio 2, it thought we said 'baby C music to'. There were a few more instances where it misunderstood us, which didn't happen as often with Alexa or Google Assistant.

Good for

  • Controlling your phone - Making calls and texts is best with Samsung's assistant.
  • Voice search - If you need help finding something to watch and you'd rather not fiddle around with an on-screen keyboard then using Bixby voice search on its 2018 TVs is invaluable
  • Samsung's SmartThings is one of the better smart home systems and you can control compatible devices with Bixby either on your phone or TV

Not so good for

  • Accuracy - Bixby's answers aren't as accurate as the ones you get from Alexa or Google Assistant, and it recites from websites too often rather than giving quick answers.

Our verdict: Samsung's smart assistant still has some learning to do. It's best for controlling your TV and phone, but can't match Alexa or Google when it comes to answering questions.