I tried almost everything available and chose UB Reader (for epubs) because of it's offline dictionary support (non-native speaker). I use Cambridge audio dictionary as my offline dictionary. For Mobi books Kindle app is undoubtedly the best app in the market.
If google play books integrates features like: copy text, offline dictionary, google search, wikipedia search then I will go back to google play books.
Maybe you can try Mantano Ebook Reader Premium or ezPDF Reader Multimedia PDF. I like to read epub using Mantano Ebook Reader Premium because you can increase/decrease the fonts under display settings (A+/A-). ezPDF also can read epub but I prefer Mantano. I use ezPDF to read pdf because of the 2 page settings.
Cheers.
May I know in what way is Moon+, more superior as compared to Mantano Ebook Reader Premium or ezPDF Reader Multimedia PDF?
I have Aldiko, Nook and Kobo on my android phone and they all work very well. With kobo and Nook you need to register to activate but then you can side load whatever epub books you want. And best of all they apps are all FREE!
Before I'd tried Mantano, I'd been believing that Aldiko was the best for epub's . Aldiko is good. It works well with most epub eBooks. But it works very badly with eBooks that contains large images. It doesn't fit large images. So the images are cut. That is very bad and ugly. But, Mantano works perfectly! I can highly recommend Mantano as the best epub reader for android. For mobi, I believe that Amazon Kindle is the best.