I always preferred Kirby. He was always an extrememly fun character to use (in my opinion), and I generally like his gameplay over King Dedede and Meta Knight.
Eep. I can't decide whether it's King Dedede or Kirby. Kirby is really fun to play as, but I'm sort of better with King Dedede. Meta Knight I used to like, but I can't really get the hang of him, I prefer someone with more power.
King DeDeDe is way to slow and bulky for me (this is why I don't like playing as Bowser, DK, or Wario too much). I chose Kirby, because he is fun to play and he has some good attacks (even if he doesn't swallow someone).