Valor. I find it is a drag to level and often times I am hampered by the lack of magic usage. In my original PlayStation 2 play-throughs, I used to swear by Valor, but now I hardly use drive forms until I get Limit Form. That is, of course, outside of leveling them all for their Growth abilities using Agrabah's Mushroom and the Merry Go Round in Christmas Town.
I used to hate Wisdom form, but at higher levels Wisdom can wreck face. I tend to use it a lot more since 2.5 was released than I used to several years back. Now, if we couple that with the fact that you can knock enemies out of their attack stances using quick run; like dancers and their obnoxious grapple move or berserkers as they prepare to use berserk, it's a no brainer as to why its useful.