Episode II by far!
I like Episode I, although I agree with Bob, in that it could have done with some more character development, but it some ways, the more I see that film the more I like it.
Now for Episode II. When I saw that in the cinema, I was totally blown away. I thought the story was excellent, and I really liked the way that the story slowly unfolded and also the way in which Anakin's character has developed.
I know there is more to a film than special effects, but I have to hand it to these guys. ILM did the most amazing job and one of my favourite scenes is when Anakin and Obi Wan are driving in mid air. Seeing that in the cinema was amazing. You felt like you were actually in that car. I also loved the scene where Yoda fights Dooko. I thought that was done really well.
Having recently seen the extras on the DVD (they're about 3 1/2 hrs long!) I was really impressed and I really don't understand why people slag off this film. To my way of thinking, it's brillaint, and I really think that George Lucas in back on form, which gives me confidence in Indy 4!
"You know I don't like it when you do that!!"
"Wow! Go Yoda!"