I don't know about best, but I like Chipocrite
I blind bought his Hit and Run CD a few years ago at MAGfest and liked it a lot.
I actually haven't kept up with him since then, so I'm glad this thread made me look him up and find out that he has a bunch of new stuff out that I've got to listen to.
I've gone to all his concerts at AnimeNEXT for the past few years. I hope he's there again this year it's always amazing especially after a few drinks I just let the music take my away!