Phantom Menace was the only good prequel. True, it wasn't very good, but it's a hell of a lot better than the other two. There's nothing redeemable about AOTC except for Christopher Lee, who is criminally underused. And the only good part of ROTS is the Order 66 sequence. That's it. The rest of that movie is terrible.
It's easier to count the "good" moments in those films because there are so few. For TPM, on the other hand, it's easier to count the "bad" moments, because while there are a great many, there's also a lot of good in it.
BAD
- Midi-Chlorians
- Gungans
- Jar Jar (he deserves his own count, apart from the Gungans)
- Planet Core sequence
- Podrace
- The way the Jedi are portrayed
- The way the Sith are portrayed
- How the Republic seems to be set up in the most illogical manner ever
- How political the film is, in spite of the fact that the politics don't make sense!
- Yoda's portrayal (repeat throughout the PT)
- Jake Lloyd. In fact, Anakin in general.
- "Cute" humor / any time battle droids talk
- Anakin builds Threepio?!
- Anakin builds anything the story requires him to build?!
- Padawan instead of Apprentice
- The Padawan hairstyle
- A boring space battle
- Ric Olie
GOOD
- Darth Maul
- Lightsaber duels (the only time I can say this for the PT)
- Liam Neeson as Qui-Gon
- Terrence Stamp as Chancellor Valorum (though he's criminally underused)
- Coruscant
- Ewan McGregor as Obi-Wan
- Watto!
- Ian McDiarmid (though once he becomes the Emperor in ROTS ... ugh)
- Actually having a death that the audience is invested in (Qui-Gon)
- Shot on film!
- The fact that it had a coherent story with a beginning, middle, and end, unlike AOTC or ROTS.
As you can see, the bad outweighs the good, but there's still quite a bit of good - especially that last one.
Ideally, all the prequels would have, you know, not sucked, but they did. But TPM is the best of the bad ones.
TESB - 9/10
SW - 8/10
ROTJ - 6/10
TPM - 4/10
AOTC - 2/10
ROTS - 2/10
(I think I've ranked the six films in another thread, but I don't remember if the ratings I gave them are the same. My apologies if I've contradicted myself here.)