I use Default. I'm used to how Rock Band Unplugged plays, plus I can play quick LLR patterns better with my thumbs.
I've only been using Default since I got the game (PS3 user here). Haven't even bothered to try the other control schemes. I'm gonna try them out soon, though.
I use the default control scheme. Left on D-Pad and A button! :D
Freakish is better for me in matching the movement of the notes... it makes sense in my head, but it just feels more tactile and accurate. When big, fast solos or really abnormal drum tracks are in play, I switch it to normal. I wish there was some way I could hot-swap the controls because right now I will actually stop the song, switch, and continue playing.
The Piano intro in Death on Two Legs comes to mind for this scenario.