I have to agree with MTM and OwP for now and say…all of them!
While I often have an inclination to think “all of them except Toy Story 3”, I’ve been thinking about how strong and impactful it still was. I had high hopes for it and while it may not be entirely perfect, it had some of the best heartfelt and funny moments out of any of the Pixar films. I still have to remember that, which is why I have trouble ranking the Pixar films. Besides some misc. toys not being around in this film and some dark parts, this was pretty much the best film it could be. For me, I also think each of the other Pixar films are the best they can be, for me anyway. I mean, what else could you ask for without realizing that you’re probably being too picky - for a movie. I don’t know, I just don’t really criticize movies I watch, especially not Pixar’s golden treasures. I give everything a fair chance and sort of think that disliking a movie is a little ridiculous, at least nowadays. If it’s offensive or immoral, I suppose, but otherwise I either like a movie (which are most of the ones I see), or I might not care for it.
If I did rank these, it would probably be linked to a certain category like, “how emotional are they” or “which is the funniest?” or “how elaborate are they?” That’s just me.
Nostalgic: Toy Story & Toy Story 2
Funniest: A Bug’s Life, Toy Story 2, Monsters, Inc., Finding Nemo, Ratatouille, Cars 2
Personal: Toy Story 1 & 2 & Cars 1 & 2, Ratatouille
Exotic-looking: A Bug’s Life, Finding Nemo, Up, Brave
Best action: The Incredibles, Cars 2
Emotional: WALLE, Up, Toy Story 3, Brave
Inventive: Monsters, Inc., Cars WALLE, Brave
You get my point. See? Everyone’s a winner with me, for different reasons. So overall, I rank 'em all equally!