When I tried an Amazon Echo a few months ago, my main problem was Amazon's lack of an ecosystem. Amazon doesn't really make productivity apps-or any apps at all outside of media and shopping. Pretty much everything you asked "Alexa" to do got dumped into the Echo app.
The "OK Google" hotword performance is absolutely incredible; It always answers, and all your other hotword capable devices hive mind together to intelligently pick a single device to respond to you, A great media product; For audio there's a loud, crisp speaker, and a great mesh audio capability.
Most of my favorite voice commands from the Google app don't work-no reminders; messages; or creating calendar events; Do you want to know exactly what voice commands are supported for each service and function Nobody knows!