Amazon has announced new versions of its Echo smart speakers that promise improved sound and voice recognition.
The basic model also allows its shell to be changed to give it different looks - a feature already offered by Google's rival Home device.
A larger Echo Plus adds a "home hub", letting it control smart light bulbs and other third-party products without a separate data-linking device.
And the Echo Spot has a screen, making video calls and camera feeds possible.
Amazon has never released sales figures for the earlier Echo line-up.
But researchers suggest it and its smaller sibling the Echo Dot have been the best selling devices of their kind.
The Echo family accounts for 75% of the US market for internet-connected speakers with built-in smart assistant functionality, estimated Consumer Intelligence Research Partners earlier this month. It suggested 15 million devices had been sold to date.
The new Echo is smaller than its predecessor and benefits from a dedicated bass tweeter.
It launches with a choice of six swappable shells that come in different materials.
It will cost £90/$100/100 euros - making it about 40% cheaper than the previous version, as well as undercutting the £129 Google Home.
The Echo Plus - which is compatible with the Zigbee smart home protocol - costs £140/$150/150 euros.
And the Echo Spot, with its 2.5-inch screen and built-in camera, has been priced at $130. It will launch in the US in December but has not yet been given a release date elsewhere.
"Amazon was first mover in this market, so it had an advantage over some of the others that entered the same space," commented Blake Kozak from the IHS Technology consultancy.
"But it's incredibly important for them to do this refresh - the original Echo came out in 2014 and the hardware hadn't been updated since, although the software and back-end services have been improved continuously.
"Since then we've seen other more 'premium' systems get announced - with higher quality speakers - so, Amazon needed to be seen to match the competition."
Many of those newer systems also feature Amazon's Alexa assistant and will not be seen as a threat.
Amazon has previously said it sells its speakers for roughly the price it costs to produce them, since its ultimate goal is to use Alexa as a means to drive sales of other goods and services.
But at Berlin's Ifa tech show earlier this month, several big name manufacturers - including Sony, Panasonic and JBL - launched systems powered by Google's rival Assistant.
Further competing systems are expected before the end of the year, including:
At its Seattle event, Amazon also announced Echo Buttons - small Bluetooth-based buzzers that can be used to play games on its speakers, including a forthcoming version of Trivial Pursuit.
In addition, it revealed the Echo Connect, a device that connects to a landline and turns its speakers into speakerphones.
And it announced a deal to bring Alexa to some of BMW's cars, including its Mini brand.
"Amazon has the momentum in the smart speaker and voice assistant space," said Geoff Blaber from the tech consultancy CCS Insight.
"These announcements are designed to deepen its role in our daily lives.
"This raises the bar significantly for Apple and Google."
By Dave Lee, North America Technology reporter
Alexa is breeding!
Amazon has clearly been working incredibly hard to capitalise on the success of its smart assistant hardware. But I'm concerned this new line-up is now so complex, all but the most knowledgeable customers will be baffled as to what features they're getting for their money.
The choice is enormous: Echo, Echo Plus, Dot, Look, Spot, Show, Fire TV, Fire TV Stick, not to mention the Dash Wand.
Alexa's success to date has been about simplicity, and if I was its marketing team, I'd be very worried this flurry of new devices is overwhelming. As for the Echo Buttons... cute idea, but they'll need to do much more than just let you play games.
Amazon has the chance to do for home automation what Apple did for smartphones.
When we talk about the iPhone, we always say Apple's achievement wasn't in making the technology - others had done much of it first - but making that tech accessible and enjoyable to the public at large. I believe Alexa could be that product for smart assistants, but it's far from being a done deal.
It all makes Google's launch next week a very interesting one.
The company needs to announce a smartphone better than the upcoming iPhone X, and now a home assistant set-up that is stronger than what Amazon showed us here today. That's a huge ask, even for Google.