My favorite... A New Hope. After all, it was the first to be released way back in 1977. It endeared itself into popular culture and launched the whole Star Wars franchise. Being the first release, it is the one which is also the easiest to enjoy as a stand alone movie. There was no pressure to link it to the past or to leave a trail to the future. One could enjoy it simply as a sci-fi adventure.
Its popularity was such that it prompted Paramount Pictures to get in on the "space" thing against its rival 20th Century Fox by resurrecting the Star Trek franchise starting with Star Trek the Motion Picture. This of course eventually led to the expansion of the Star Trek franchise itself.
(Wow, Trekkies owe their current incarnation to Star Wars, imagine that)
Anyway, as far as the worst Star Wars movie goes, I agree, the Phantom Menace. The only redeeming part of that film is the final battle in which Darth Maul kills Qui-Gon and then Obi Wan kills Darth Maul.
OK, as you can see, girls can get their geek on too. LOL