Well, dreamworks does have some darn good movies to its name. SHreks 1 and 2, and to a lesser extent the 4th Shrek. Ants and the road to el derado also come to mind. ANd god help you if you didn't like Chicken run and Kung-fu panda.
But Pixar is a strong contender. The toy story trilogy is among the best movies ever IMO. Finding Nemo, Monsters Inc, Wall-E and UP.
Really I like both. They have both contributed some of my favourite movies of all time, and even the movies I didn't care for so much ussually kept me entertained the first time through. Really, between the two they've only made a few movies I dislike at all.
So yeah, I love both.