I prefer the classic pro (11.75 diameter) shaft. If I'm not concentrating and hitting the cue ball right you know it. It make me focus more on where I strike the cue ball and the alignment for the shot. Also, you can soften your stroke and get more action on the cue ball without moving to far from center ball hit. I played with the OB team for a few years and could not get use to the ob-2 with the quite hit. As an old school player I play by the sound on contact. When Royce came out with the classic line it fit my style of shooting and been playing with the classic pro ever since!
Different strokes for different folks, so just try them and see which fits you style of play.
Good luck!