Ray from The Princess and the Frog
The only character without a hint of Sci-Fi to make my top 5 (and choosing between him and Stich was hard,) Ray is just... Ray is Adorable. His blind faith in love was inspiring to me, and you just really cared about who he was and what he stood for. He got me really welled up a few times.
Buzz Lightyear from Toy Story
The man, the myth, the legend, the guy with the karate chop action and little light-bulb that blinks; who didn't love Buzz as a kid? Partly for nostalgia's sake, and partly because he's a hilarious and fun character, Buzz remains one of my favorites. Buzz simply never gets old.
WALL-E from WALL-E
I don't even know where to begin on this one. WALL-E made audiences fall in love with him before he even said a word, myself included. He's a sweet character full of hope and light that can be related to far too well to be a robot living 700 years from now. He's the guy you wish was around on those days when you get tired and bitter and forget that love is the most important thing. He's like everything good about humanity in a box.
Sprx from Super Robot Monkey Team Hyperforce Go!
You know, that show on Jetix? Anybody?
Anyways, one of the things I loved about SRMTHG was the surprising depth of the characters and their relationships with one another. Sprx, IMO, was the most well developed character I've seen in a kid targeted animated series in a long time. He has insecurities and desires and the writers don't shove it all in your face but you still understand him by his subtle actions. He jokes around and flirts and acts like a moron, but also has a very valorous streak and street smarts when it comes down to it. You really see his grievances and root for him.
EVE from WALL-E
EVEEVEEVE! EVE is AWESOME. I fell in love with EVE the moment I saw her character design; she just looks so cool and she's hardcore and she can blow holes in boulders.
But more importantly, EVE has an amazing character development arc. The story of her learning what it means to live is just as root-able and endearing as WALL-E's story, and it's done in such a natural feeling way that's so beautiful.
Plus, again, she's cool.