I love Ayu, Utada, Do as Infinity, Crystal Kay, BoA, Morning Musume, and a bunch others I'm too lazy to list out right now.
I was actually also hoping for some recommendations since I've been out of the loop for a couple years with jpop. Who's hot right now? some new good songs? Also I'd prefer girl singers, I just can't get into guy jpop. Feel free to list old songs/artists too.