Since people are covering The Lion King and Emperor’s New Groove etc here are a few that might not have been covered yet:

•Don Hertzfeldt’s work, lots of people caught Rejected as a wacky internet staple back in the day, his newer stuff as well as classics like Billy’s Balloon are always a great time. Www.bitterfilms.com

•Waltz With Bashir, a surprisingly moving and even handed tale of the ‘82 invasion of Lebanon.
Trailer (there’s a variety of computer aided animation methods in this but it’s mostly a 3rd with 2d shaders effect so I’m counting it)

•Princess Mononoke, the perfect anime to show people who aggressively avoid anime lol. Beautiful naturescapes, a story that’s easily accessible and doesn’t lose its impact being ported over from another culture of storytelling tropes, and if you’re doing the dub thing, voice actors who aren’t distracting or frustrating like so many dubs. Just a solid flick all around. Trailer

•The Prince of Egypt - beautiful animation, memorable songs, an amazing cast list, I’m not one for religious stuff in general but this is as fine a tale as you’ll find out there. trailer