For me, it had to be the Titan. When the girl started climbing out of the atmosphere, it looked like a predator going for the kill. I guess that was the very moment I fell in love with the new Enterprise.
Then again, the movie had loads of epic scenes. I laughed my *** off when Kirk was in Kobayashi Maru simulation, acting all goofy and the others going "what the hell is he doing?!?"