Hmmmmm that's a tough one. I'm not always listening to one artist and sticking to him/her. I always branch off to other artists and end up having many favorites.
But favorite singers in america? Hmmm. All the stuff Nicole, Fergie, Beyonce, etc. sing are meh. Don't get me wrong, they sound good and I like their stuff enough to say they're good. But, they don't suit my "swag".
Recently if I were to list people that can get me grooving with them, it would be:
Sade
Alicia Keys
John Legend
Esperanza Spalding
Aaliyah
Luther Vandross
Keith Sweat
Robin Thicke
Aside from that, I can appreciate talent from singers who aren't as popular. Especially if it just convincingly caught my attention. Like this vid I saw greatone posted(many thanks for this find). Hate to sound like an biased ass, but this is true talent of what is singing.