short version: 1 is so-so, 2 is great, 3 is absolutely awesome
Reverse 1 and 2 and you have my opinion.
Super abridged exposition:
Phantom Menace may have a lot of problems, but the pod racing, Qui-gonn, and final battle make up for it. I wouldn't call it an amazing movie, but it is still a very good one. Duel of the Fates is also one of the best tracks John Williams has ever composed.
Attack of the Clones is the poster child for everything wrong with the prequels. Too many important things happen off screen. Dooku and his betrayal mean far more to the Star Wars universe than the movie would have you believe. Anakin and Obi-wan's relationship is largely unexplored. Anakin spends most of the movie wasting all of his potential as a character. On the other hand, I don't think it's terrible. There are some pretty good scenes (Yoda, the factory scene, the arena scene) and it sets up the next movie decently.
Revenge of the Sith is my favorite Star Wars movie. It is a flawed masterpiece. Anakin is much more interesting in this movie and finally lives up to what you'd expect after watching the original trilogy and imagining a pre-fall Vader. Palpatine is a menacing and effective villain. The story is a culmination of everything that's been hinted at not only in the other two prequels, but also in the original trilogy. We see the fall of the Jedi, we see why their philosophy was flawed, we see how their arrogance worked against them. We see how Sidious played everyone like fools. We see how some people realized shit was going down (Windu, for one) but couldn't do anything about it in time. We see the glory days of the republic and watch it burn and rise again as the empire we loved to hate in the OT.
So, yeah, 3 > 1 > 2.