I don't know what RSS reader most people use, but I have tried them all. Having done so, I always come back to NewsRob. It has the best UI and features. It is also the only Android-based RSS reader that truly syncs with the Google Reader. Here is a review featured today on Android Tapp:
NewsRob Android App Review by AndroidTapp.com | Android Tapp. Android App Reviews
If you know of a better RSS reader, please share.