I think most of Jame's Cameron's deleted scenes are awesome.
In the first terminator, I think the scene where Reese sees all the natural beauty in the world and just breaks down was beautiful, and allows the character to show his true nature behind his war scarred facade.
aliens- the scene with the aliens attacking the turrets is still tense as hell.
In X3, I actually prefered the cut juggernaught/wolvie fight. I think most of x3's scenes would have been damn great actually.
In Dracula 2000 (dont laugh) there is an excellent scene which shows how good Gerad Butler is where his character, dracula/ judas, is talking to a cross with Jesus. Even though its an inanimate object, its like he is talking to an intimate friend and shows you he isn't just an immortal monster, and how he got kinda screwed by fate.
I have never seen this scene but several sources indicate it exists- and it sound FANTASTIC. In lost boys, at the end of the movie, as the movie fades out- it returns to the cave, and in a mural we see Max, painted as he was in the 1800s. I thought that would have been a cool little moment.