[JMikeD]

I have an Echo, Google Assistant on my iPhone 6, and of course Siri. I've used all three a lot and done comparisons. To my mind, here's not a clear winner here.
Siri is better at giving you answers to questions that don't have a single, clear-cut answer, whereas the Echo and Google Assistant (presumably the same software as Google Home) will offer only a single answer.

One of my tests is to ask for the following conversion: "Convert 40 miles per gallon to liters per one hundred kilometers." Siri offers a selection of web sites that will do conversions if I go there and enter the information, the Echo says it doesn't know that, and Google Assistant (GA) gives the correct answer: 5.88 liters per one hundred kilometers.

Echo will turn on/off all my Insteon home automation devices. Google and Siri won't.

Siri will go everywhere with me (so will the GA for iPhone). Siri has secure encrypted communications. Echo doesn't seem to encrypt, but doesn't communicate with Amazon until the wake word is spoken (you can toggle a beep that sounds at the beginning and end of the communication, but of course that could be faked). It's unknown to me whether the GA encrypts. It doesn't seem to do anything until you launch the app, so it's unlikely to be listening all the time.

So none of these things are where I'd like to see a good home assistant device. I'm treating the Apple HomePod the same as Siri. I don't need an expensive speaker, I already have a nice 7.1 surround system to listen to. So I'm not the market that Apple is going after with the HomePod.