My first favorite character is no doubt Malcolm. He's smart, he's funny, he is one of the best narrators I've ever seen, and he's a cold-hearted cynic. His personality is unlike everyone's around him, and he is ultra-crazy when it comes to girls.
My second favorite is Stevie, he's so underrated, but he is so badass. After season two, he's sure of himself and after the carnival, loves to stir up trouble with Malcolm. The best part - is that he is so innocent in the adults' eyes and it's a case of 'oh that darn Malcolm!' and Stevie usually gets away scott-free! He's just a poor helpless Krelboyne to most people, but he secretly kicks more ass than Reese.
My third favorite has to be Cynthia. At first I hated her because I thought she was creepy and over attached. But then I realized Malcolm did the same things in different forms. And in the later episode, she is putting herself up for ridicule to save Malcolm by admitting that she and Malcolm had sex. (When they really didn't) I mean really, girls go through enough crap (especially ones of her bust size) of being sluts for no reason, and she just sacrificed herself so that Malcolm wouldn't have to go play soldier. Seriously, that is some selfless shit right there.
My fourth favorite character would have to be Francis. Even though he hates his mother, made Dewey drink diseased rainwater for a stupid cookie, and married someone a month after they met, he is hardworking, determined and will rebel against all odds. He also made some stupid, bored Marlin seniors stop in their tracks just by describing his mother, Francis must have some pretty tough skin to get through that. While he is certainly less than perfect, his flaws create intrigue.
My fifth favorite character is Dewey. Who couldn't love sweet, innocent, slightly annoying, Dewey? Refreshingly honest and an extra dose of cute is just what the doctor ordered for this train-wreck family. Dewey is so scarred by the final season, but doesn't use that to bully tiny itty bitty Jamie, but to have a different bond with him. Dewey remains mostly uncorrupted and sweet through all the crap and the world throws at him for no reason. Dewey - like Francis, is one hell of a trooper.