Here are some of my fav scenes:the tent scene in eclipse,jacob phasing in front of charlie in BD 2,the battle vision scene in BD 2,the Kiss with bella & jacob even though it meant nothing for them,the wedding/honeymoon/ birth scene. I can't think of many scenes i hate but some movies could've added еще like BD 2 should've had еще dialogue for the vampire covens. They stood around too much. And Renesmee could've looked еще realistic.
From the entire saga? I have to say my favourite scene is probably when Alice comes back in New Moon, which I would describe as...heart-wrenching. And my least favourite could be when Mike asks Bella out and she accepts, also in New Moon which I would describe as a let-down.