It's amazing how so few people know about Titan A.E. I was about 6 years old when that came out, but I can still remember a good part of it.
The only motion picture company that has yet to let me down thus far is Pixar. I've watched every single film they ever released, and have yet to miss one.
For 2-D movies, I love the good majority of the old Disney cartoons (I grew up on them, in fact) and love Hayao Miyazaki's works. I have quite few; and for Castle in the Sky and KiKi's Delivery Service, I also have the Taiwanese/Chinese dubs (we had those first, actually...).
@Shad: Princess Mononoke is awesome. I loved it so much, in fact, that I watched it way too many times...
Oh yeah, Porco Rosso is also pretty good.