Probably core pathfinder. The chap is running some sort of playtest, and since the Pathfinder Boon or Bane thread here has convinced me that any worthwhile feedback will never make it into the ears of someone with the potential to do anything with it, I just want to have some fun. Wizzards and the other prep-casters... too much book-keeping for me. Didn't like them much. Didn't stop me from making wizard gishes in 3.5 (hey, I'm a fan of sword and sorcery) but damn, was that a PITA.
Incidentally, I was Rashomon on the 339 CO Boards. Now I'm just another dumb guy. Hooray.
EDIT: Also, if this were 3.5, I'd already have a bunch of mental shortcuts as to what I want. The problem then would be "which exact build do I use to twink out the funky character archetype I have in my head?" Since this is PF, my knowledge is extremely minimal (I just got the PDF today, for instance) and it'll take me a while to fully digest it and make the right decisions. I'll probably have to echo the popular opinions and say that fighter types got more toys, but you don't use toys to kill dragons.