Dex. Everyone pinks at least a mediocre Dex, including Clerics, as it benefits to PC longevity due directly via a higher AC. Wizards, barbarians, monks, rangers, fighters, they all take at least a 12 if not more to protect themselves with agility. And naturally most parties have a rogue, so I think the stat gets more points than any other, perhaps followed closely by Int for the skill points.