Howl's Moving Castle, just because it is perhaps the most beautiful full color hand drawn animated movie I have ever seen.
Grave of the Fireflies was seriously touching though. Strangely, Princess Mononke is my least favorite because I have no idea what was going on during the film at all.
http://www.youtube.com/watch?v=F1gWECYYOSo
Please Watch/Share this video so it gets shown in Hollywood.