It may not be the best cartoon out there, but Atomic Betty isn't bad.
Betty is an average fourth grader who doubles as a Galactic Guardian (that is, she defends the universe). Her crew consists of herself, the alien Sparky, and the robot X-5. Most of the humor in the show comes from the clash of personalities of the sloppy Sparky and the meticulous X-5, although the villains provide some good laughs as well.
Speaking of villains, the main villain in this show is Maximus IQ, a sinister cat who desires to destroy the universe. He is "aided" by his bumbling sidekick Minimus (who is a sort of Jekyll-and-Hyde personality). Other villains include the Chameleon (a shape-shifter) and Iciclia, queen of an ice world.
Though it may not be Kim Possible or Phineas and Ferb, Atomic Betty still provides some solid entertainment. The animation is solid and the characters are interesting enough to give it a chance.