Dreamworks.
Shrek, Kung Fu Panda, Madagascar, Over the Hedge, How to Train Your Dragon, and many more of their movies are awesome, full of action, and have great, memorable characters. I also love the humor in them, and they're great to watch again and again.
It's not to say Pixar is bad. though. Many of their movies are good, but I just don't find myself getting as attached to the Toy Story series, Wall-E, Cars, Up, and so on. Many of these movies I watch once, and they're good for that one time, but they're not the kind of movie I would watch again and again. I'd have to say, we own way more Dreamworks movies in our DVD/Blue-Ray collection than Pixar movies.
As far as animation quality goes, I'd say they're both equal.