OK, I predict I may go on a long ramble here as I love animated films. This is all just my opinion of course, but you should respect it because I know my shit!
For something a bit different try Perfect Blue by Satoshi Kon, who is better known for his more recent animated film called Paprika (which is also worth a look). Perfect Blue is really interesting, dark and I guess rather Lynchian in its style. It\'s about an ex pop singer who starts to loose her grip on reality when she starts being stalked. Mature and affecting stuff for sure.
Tokyo Godfathers is a fine alternate Christmas story about 3 homeless friends who find a baby and decide to keep it. Er, it\'s hard to describe without making it sound crap to be honest, but it\'s good and quirky, with a slow, laid back, but rewarding pace, some great looking scenes and it is in no way as cheesy as you are probably imagining!
Heading towards the other end of the scale and complete fantasy, you should definately check out all of Hayao Miyazaki\'s work. Spirited Away is lovely, but I think I\'d go for the simplicity of My Neighbor Totoro or the all out crazy heroics of Porco Rosso.
Akira\'s great obviously. That\'s what got me into Japanese animation I suppose. Katsuhiro Ôtomo\'s recent passion project Steamboy, although horribly flawed, does have some absolutely jaw dropping steampunk technology on show and it\'s worth checking out for that alone.
Moving to US stuff, the Iron Giant is an often overlooked classic. It\'s directed by Brad Bird, so that should give you a clue of the quality.
Monster House was a film I loved last year. It was criminally overlooked by most people and deserved the Oscar. The director Gil Kenan shows masterful knowledge of characterisation and pacing. He\'s going to be an animation superstar in a few years. Oh, and it manages to nicely capture the childhood to adulthood transition phase of life that makes live action films like Stand By Me so successful.
I think the best traditional Disney is the Jungle Book, just in case you haven\'t seen it. The animals are so perfectly animated it hurts.
Best digital animation is still Toy Story. Perfect concept, amazing script (Joss Whedon and Joel Cohen you say? Holy crap!) and a brilliant look.
Watership Down manages to be terrifying, heart breaking and moving at the same time. It\'s brutal to watch though, have a box of tissues handy!
And if you can get hold of it, the UK TV series Trapdoor has the most amazingly vibrant stop motion animation you\'ll ever have the privilege of seeing.
I guess I’ll stop now. That should keep you going for a while.