I'm just trying to field a discussion here as a way to discover new animated movied I may have overlooked. I just finished watching Frozen today for the first time and it left me feeling a little nostalgic because Frozen was able to connect with me the way Lion King did 20 years ago, and the way Up, Wall-E, and Finding Nemo have been able to do after that.
Anyways post your top 10 favorite animated films of all time also an animated film you thought was overrated. Here's my list:
1.) The Lion King
2.) Aladdin
3.) Up
4.) Toy Story
5.) Frozen
6.) Finding Nemo
7.) Wall-E
8.) The Little Mermaid
9.)How to Train Your Dragon
10.)Grave of the Fireflies
Most overrated: Spirited Away (I thought the animated was great, but the story was not moving or compelling, it was just weird)
Spirited Away it 10 times better than all the other films in that top 10 of yours for me at least

. I have a top 50 animations thread somewhere in the forum, here was my top 50 ranking as of August 2013:
New iteration of my top 50 animations (new additions in bold):
1 - My Neighbor Totoro
2 - Puella Magi Madoka Magica the Movie (parts 1 & 2)
3 - Nausicaa of the Valley of the Wind
4 - Princess Mononoke
5 - Grave of the Fireflies
6 - Spirited Away
7 - Porco Rosso
8 - Only Yesterday
9 - Whisper of the Heart
10 - Kiki's Delivery Service
11 - Castle in the Sky
12 - Rurouni Kenshin: Trust and Betrayal
13 - Howl's Moving Castle
14 - Millennium Actress
15 - Evangelion 2.0
16 - Children Who Chase Lost Voices From Deep Below
17 - Summer Wars
18 - Scott Tenorman Must Die
19 - The Man Who Planted Trees
20 - 5 Centimeters per Second
21 - Tale of Tales
22 - Paprika
23 - Summer Days with Coo
24 - Ponyo
25 - Gauche the Cellist
26 - Hedgehog in the Fog
27 - Akira
28 - Wall-E
29 - Wolf Children
30 - The Place Promised in Our Early Days
31 - Ghost in the Shell
32 - Castle of Cagliostro
33 - Night of the Galactic Railroad
34 - UP
35 - Evangelion 1.0
36 - Horus: Prince of the Sun
37 - Memories
38 - Ratatoille
39 - Wings of Honneamise
40 - The Illusionist
41 - From Up on Poppy Hill
42 - The Plague Dogs
43 - Tokyo Godfathers
44 - Dimensions of Dialogue
45 - Galaxy Express 999
46 - The Incredibles
47 - Mind Game
48 - Watership Down
49 - The Triplets of Belleville
50 - Fantasia
Now though I would increase the ranking of PMMM to 1st place, decrease Totoro to 3rd place, Nausicaa up to 2nd place and add a couple of new films, though not enough not significantly change the ranking. I would add a couple of honorable mentions:
- Bambi
- Pinocchio
- Dumbo
- Perfect Blue
- Waltz with Bashir
- Persepolis
- K-ON! The Movie
- Urusei Yatsura 2: Beautiful Dreamer
- Angel's Egg
- Ghost in the Shell 2
Another animation fan in the forum is Jal90, he also has a top 50 animations that you can find using the search function.
Most overrated? I might say, Toy Story, given it was ranked 5th place in the Sign and Sound poll among animations, right behind Spirited Away and Tale of Tales and tied with Princess Mononoke, vastly superior films IMO. I rate it as
-, it's a well made comedy film but nothing really special overall.