Definately The Lion King... I was in 2nd grade when it came out- it had it all:

Grammy winning soundtrack score (Hans Zimmer)
Grammy winning song lyrics (Tim Rice, Elton John)
Grammy winning song (Can You Feel The Love Tonight?)
Great cast
Beautiful animation
The highest grossing animated movie EVER (Finding Nemo doesn't really count as animation, it's CGI)
4 soundtracks- Original movie, Broadway, Rythmn of the Pridelands, and Lion King 1 1/2
2 sequels (although they sucked)
A successful Broadway show

What more could one want?