Not a question I can answer quickly...both companys have movies I like and movies I don't.
For Pixar there are movies like UP, Wall-E, Toy Story 3 and for Dreamworks there are Kung Fu Panda, How to Train your Dragon or Wallace&Gromit Curse of the Wererabbit.
As for the ones I don't like...Pixar has Finding Nemo (a movie everybody seems to like but me) or Cars, while Dreamworks has Shrek (another movie everybody seems to like but me) or Madagascar.