I'd say it has to be wisdom form for me. Sure, the magic combos do make it powerful, but quick run is finicky and proves only to be useful as a sort of slightly worse dodge roll with pause time in between uses and is used only to traverse world maps slightly faster, and overall the magic bullets shooting from the keyblade are pretty weaksauce. Valor form is basic, sure, but at least it has superior weapon strength and the useful high jump with it. Master form is an amalgamation of both, final form (need i say more?), and limit form gives you super useful limits and dodge roll so I consider it good.
I'd say anti form but honestly it is pretty powerful and the story reasons behind it save it for me.