Well, so far, KFP seems to be standing on its own well enough...I mean
Antz = A Bug's Life. Obscure worker ant wanting something far better who is living a life under some form of oppressive overlord, who eventually overcomes his awkwardness and falls in love with the princess. Of the next two, Antz seems more like the rip off of A Bug's Life. Though it was released first, it went into production long after A Bug's Life. And they should have had those WASP wasps more. Those WASP wasps were awesome
Madagascar = The Wild. Animals who get out of their familiar (New York) zoo surroundings and end up in the wilderness by boat. Complete with a lion and giraffe in both groups...though, I found the reason for getting into the wilderness in The Wild more interesting than Madagascar. And if I remember correctly, the Wild also went into production before Madagascar.
Happy Feet = Pebble and the Penguin. Odd penguin out gets separated from home and must get there to save the day and get the girl. I still like Pebble and the Penguin better than Happy Feet. Too much of an environmental message in HF for me and they SHOULD HAVE KEPT THE SEAGULL SCENE! Steve Irwin Seagull > Steve Irwin Elephant Seal!
I really feel like KFP is the best of the whole lot. It had a major lack of pop culture references, one factor I love, the soundtrack makes me drool, and I sort of like how Po has developed between the first and second movies, but he's still the same ol' guy in many ways. And it definitely has the best sequel villain. "Part of you here, part of you there, and part of you waaaaay over there staining the wall *eye twitch*" Looks ridiculous on text, "crud, that guy's serious D: !" on film. Tai Lung was okay, but he just didn't feel as "developed" as Shen to me, although they both did have abandonment complexes...and foster parents who are shorter than them. Heck, even Po has a foster parent that's shorter than them, but Mr. Ping is definitely the most delightful of the bunch XD .
And yes, they are making a third. It's pretty much a given with the cliffhanger at the end of the second film.