When it comes to intelligent assistants, you have a lot of options today that didn’t exist a year or two ago. It’s not just Siri, now there’s Alexa, Google Assistant, and someday Viv (recently acquired by Samsung). But which is best and in which use cases?

Well, Benedict Evans has an opinion on the matter.

Evans is a partner at Andreessen Horowitz and is known for his predictions and analysis of business trends in Silicon Valley. Andreessen Horowitz is one of a handful of venture capital firms working with Slack to give bot enterprise developers tens of millions of dollars. He spoke last week at O’Reilly Bot Day, a gathering of more than 200 startup founders, developers, and investors in the bot ecosystem that was held Oct. 19 at the Mission Bay Conference Center in San Francisco.

Here are 3 ways Benedict Evans thinks Alexa is better than Siri:

1. Alexa makes it easy to buy stuff

With the exception of Alexa and Facebook Messenger (leadership there has stated Facebook will take no cut of sales made on the Messenger platform), both of which added purchasing functionality to their platforms this summer, virtually every chat app platform requires you to leave the platform, typically for an app or web page, in order to complete a transaction.

Evans enjoys the ease with which a purchase can be made on an Alexa device. More than a million items can now be purchased from the Amazon retail marketplace.

“So yes, if you’re standing in front of a washing machine, and you realize that you’re out of soap powder, you could put the laundry in and then go get your phone and turn it on and open the Amazon app and order some more soap powder like you’re winding a physical dial or something, but you can also say, ‘Alexa, order me more soap powder,’” Evans said.

Want to buy some laundry detergent with Siri? Not going to happen. It may serve up some Bing search results, but chances are it just says, “I don’t know what you mean by ‘Siri, I want to buy laundry detergent’.”

2. Unlike Siri, Alexa does not claim that it can handle every question 

The cleverest part of Alexa, Evans said, is that its limitations are clear. This creates more accurate expectations, and you can use an Alexa app to find out exactly what questions you can ask.

“The problem with the voice interface, or probably the bot interface or any kind of non-visual interface, is that you don’t know what you can ask,” Evans said. “This is why Siri was such a failure, because Apple went out and told everybody that you can ask Siri anything, and you couldn’t. You could ask it for 15 things that they’ve written.”

3. Alexa removes pain points that get in the way

Evans places Alexa into a category with the Snapchat Spectacles or ChromeCast, devices that extend an app or service into a physical product.

He defines steps like charging or turning something on as friction. The ability to simply say “Alexa, order more laundry detergent” is an example of a frictionless process. There’s no need to press a button, and the battery lasts for days. All you have to do is speak.

Evans made a similar point in a blog post about the Echo earlier this month.

During the mobile app era, Google and Apple had a lot of say about how all other players used its iOS and Android operating systems, but that’s slowly changing.

“That means that this is about reducing friction, yes, but it’s also about the reach of cloud and web service companies and how they think about a broader world in which the PC web is increasingly left behind, the smartphone OS is the platform, and the platform is often controlled by their competitors and how else they can build services, beyond fitting into a smartphone API model that someone else defined,” Evans wrote.

Amazon made the right business decision by creating its own device to deliver Alexa skills, Evans said, because it gives the company a platform that is not controlled by Google or Apple. That not only extends Amazon service deeper into the cloud, so that Alexa can appear in more products beyond the Echo or Tap, it also gives Amazon more control.