I like Ash, Misty, Brock and Gary (At first I didn't like Ash, but he's grown on me!)
However, I think my favorite character is James from Team Rocket :classic:. He may go around with Team Rocket, but he cares for other people and Pokemon (Growlie!). He also has an interesting background and showed spirit by rebelling against family wishes. He also never gives up, no matter how many times he has been foiled. His team-mates can often screw him over but he shows true friendship by sticking by them.
Oh, I forgot, I also like Professor Oak, he seems to be quite a comedy character in the show and makes me laugh. I don't like the new characters to be honest.