I loe them all... but, just for fun, here's how I would rank them
Based on a scale of 1-10, and only comparing each pixar film against the others.
Finding Nemo 10/10 - An almost perfect movie, the animation was beautiful, but what really sells it is the terrific voice cast, the enchanting music, and the clever screenplay. Everything is such a joy to watch, and everyone behind the scenes seem to be having a ball.
Toy Story 2 9.5/10 One of the few sequels I feel is better than the original. The screenplay, while nearly being a mirror of the first, somehow still feels fresh and unique. Some delightful humor, and even better character interaction between the supporting cast. What really made this movie soar was taking them out of Andy's room for much of the movie and really letting them explore.
The Incredibles 9.5/10 -The screenplay wasn't near as tight, but easily one of the most clever twists on Superhero stories I've seen. Also, the best Pixar soundtrack they've had so far. The cape sequence is worth the price of admission alone. A great send-up to classic 60's spy thrillers.
Toy Story 9/10 - I grew up with this one, and despite my minor qualms, it will always be one of my favorites. I remember being enthralled by the characters and animation when I first saw it in theatres. One of the few kids movies to really capture my imagination and really send it flying at that age. Toy Story will always have a place in my heart.
Monsters Inc 8.5/10 -The screenplay isn't as great, but the interaction between Mike and Sully is terrific, and surprisingly adult for a "kiddy" flick. The relationship and bond between these two are really felt at the beginning, and I always find myself cheering them on. Unfortunately, the main plot involving the two villains I don't think is near as fun or engaging as the secondary plot between the two heroes.
Cars 8.5/10 - Where this movie mostly disappoints is with it's supporting cast. For the most part (except for Bonnie Hunt and Paul Newman) very little time is spent developing the supporting roles. Which wouldn't be near as much a problem if the supporting cast were as entertaining as some of Pixars other characters. Even with little screentime, Slinky Dog manages to be an entertaining and fan-loved character, unfortunately this movies supporting cast didn't do it for me. Instead, the movie focuses on the main characters INNER journey (which was a nice touch, in my opinion). One thing that both interested me and at the same time disappointed me was the isolation in the movie. I didn't get a sense of GOING somewhere like I usually do with a Pixar movie. This time around I felt stuck and isolated. Which was a good effective device, considering the main characters dilemma. Again, the ending makes it worth it (I loved the little car changing tires)
A Bugs Life 8/10 - This is one where the real leads are it's supporting cast. They are fun and witty, and offers the best laughs, and the most heartfelt moments. The love story between the two ants held very little interest for me, but the supporting cast arc did. I found their eventual triumph much more rewarding the two ants gettin' it on. Unfortunately, the screenplay just doesn't hold up on repeat viewings and I find myself getting bored after a while. Still, the end payoff makes it a more than worthwhile entry and better than most of the crap hollywood dredges out currently.
Again, this is just for fun, a lot of spare time on my hands lately... :-D