I'm really, really shocked to hear people put TPM as their "favorite." It's an awful, AWFUL movie.

That said, things I like about it:

Liam Neeson

okay, moving on

I liked Christopher Lee's character in AOTC. I liked the clones/gunships/battle. It wasn't tactically very sound, but it was neat. Like a big videogame. I liked the bugs, especially the king bug's voice. Um...hm. I liked the Jango/Kenobi scene on Kamino, as others have said.

ROTS:

I liked Palpatine's office. I thought the music was the best of the prequels; his "seduction" of Anakin at the opera was good. Uh...liked seeing the Tantive IV interiors again, that felt really cool. Crispy Anakin was neat. Oh, and the fall of the Jedi + the music there was brilliant, I think. Gave me chills.

So yeah, they ascend in order of watchability from 1-3. 1 is just...it's fucking awful. There's no other way to put it.