1. Batman - Perfect balance of kicking ass with emotion. He's by far one of the most interesting characters out there, and he has an incredible array of feats under his belt
2. Spider-Man - Again, interesting character, great gallery of villains, written well (most of the time), and funny
3. Joker - C'mon. Do I have to explain? This dude is THE MAN.
4. Flash - I never used to like him until I started to get to know more about him in the past few years, but this guy is a beast. Not only is he funny, but his powers are awesome. What he lacks, though, is any good villains, so its hard to read his comics.
5. Gambit/Wolverine/Magneto/Venom/Carnage - these guys are all tied, so I can't pick, but in general, Gambit's powers are awesome, Wolverine is a very interesting character, Magneto is a great anti-hero/villain with a great drive behind him and impressive powers, and the symbiotes are just killer lol.