I think maybe Im partial to II because we see a little more of Superman than in the first one.
But the first one is so dramatic. When he first switches to Superman after NOT finding a whole phone booth--
catches the helcopter
Those other saves like Airforce 1
The leap out the window when he hears Luthor's whistle and then flying around the buildings. I love the flying scenes.
And that whole diseased maniac scene in Luthor's lair. Awesome!!!