You have so many options, SCION. You have a kindle, buy kindle books, and can use the kindle app. You have a Sony tablet and reader. You can use their app. Then there are the independents like Aldiko. You must buy kobo books from time to time, as well, or you wouldn't bother with their reader in the first place. If you are downloading them as ePUBS, you are golden on many different readers.
If your choice is to buy from Google and use their app, great. Enjoy it. In Canada a whole lot of their books seem to be more expensive than they are at Kobo, but it may be different in the US as I assume you aren't wanting to cut off your nose to spite your face.