Ultimately, I voted for Vancian. I prefer spell points, but that's not because I see anything inherntly wrong with Vancian casting, but rather that I don't find it intuitive. If I were making a game for me, I'd go with spell points.
Thinking of this as "rebuilding 3.5" (changing as little as possible), I'd keep the vancian system, although I might lean for a casting method much closer to the beguiler/dread necromancer/warmage for all casters (narrowly focused spell list, you know all spells on your list, you spontaneously cast as a sorcerer off of that list).