Every smart home needs a hub. Whether you opt to use Apple's HomeKit and Siri, Samsung's SmartThings and an app, or the Amazon's Echo and Alexa.
After going back and forth for almost a year about whether I was comfortable having an "always listening" device in my apartment, I decided to take the plunge. It's been great. In addition to being able to ask the Echo a whole bunch of questions about the news or weather, it gives you the ability to interact with smart-home products using only your voice. It's amazing.
Voice operation removes a layer of friction between me and my smart-home devices that I didn't know would be there. It's so much more natural and fluid than fumbling through an app. All of the devices on this list are Echo-compatible, and honestly, I wouldn't buy a smart-home product if it wasn't.