B4 I bought my 1st echo dot (I now have 3), I reviewed which was better between Dot - Alexa & Google Play.
The main diff between dot & Alexa was the speaker & how to control the volume (ring on the Alexa & a button on the dot). Oh, & the BIG price tag that comes with Alexa! The speaker on the dot is just fine for me even with playing music. And if I wanted more out of the speaker, I could blue tooth to a speaker I already have. And I'm happy I went this route to buy the dot.
I did reviews between the Amazon products vs Google Play... census was Amazon's was better, saying Google play needed work.