I will say that Amazon and Google Play Store make up the bulk of my royalties.
Visually, Google has the nicer interface (no ads!), but their search function is not very good. You basically need to know what you want to buy. And their delivery is not good unless you buy for a phone.
For aware readers, Smashwords and Payhip are the best bets. They give you a file, DRM-free, and you can decide what you want to do with it.
If readers only knew.