I am surprised that nobody has mentioned HERCULES yet : for me it's the greatest animated movie ever made - not just really funny, but the only Disney movie based on Greek mythology - a fable on the cycle of life, brilliantly told!
The voices of James Woods and Robert de Niro make it even better - I absolutely love it; so much so that I have written my own little review about it - you can read it
here if you want to.