You say Pixar is always stressful but yet only one has ever stressed me(I should say got me tensed up as it didn't stress me out) and that is Brave the rest kinda relaxed me...I guess I must be in the minority.
I've personally thought they have been on a all time low, they just keep going lower. Toy Story 3 kinda was a fluke they finally got getting better than Cars 2, Blah, Brave...kinda bah again though its not that that bad. They were the best but then it just kinda, I don't know hit a point where they just couldn't keep the good products bettering themselves or at least equally former work. None have been detestable but they've been pushing 3, 3 and half's out of 5 on average, Cars, Cars 2, and Brave kinda made me think that they lost their seat as King to Dreamworks, and then 2nd place was taken by Disney making Pixar the 3rd which is sad since they have had a great history with animated products.
Hmm the Top 5...this is difficult.
Toy Story 3 is the favorite, it was surprisingly excellent especially after having been outgunned by other animated studios for so long. Sadly it was not the best of the year, Dreamwork's How to Train Your Dragon got it...wait no it didn't...yes it did...okay it tied with How to Train Your Dragon.
Up is 2nd How many animated movies tug at your heart strings in the opening sequence? Not even Toy Story 3 did that with me. Up did.
Incredibles is 3rd, the 1st superhero movie I actually liked. It was fun and is still great.
Toy Story, the 1st computer animated feature ever. It rightly is seen as among the best and will be seen as so for centuries to come. It was the 1st...ever of its kind...not many movies have that kind of honor.
Wall-e interesting fresh concept done in a fresh way. I couldn't help but love it. Few movies are this original.
Honorary Mention: Finding Nemo and most of the others. I love them all so my sadness that Pixar can't keep things fresh saddens me, hopefully the sequels/prequels revive them, they're awesome after all.