This is tough.
1. Sonic the Hedgehog
Sonic is a heroic character, but he's not a goody-two-shoes. He has attitude. He can be vain, but always tries to do the right thing. And he can run at the speed of sound. I always thought that would be a really cool superpower to have. I first played the game when I was 6 years old, and now here I am, at the old, old age of 29, still a fan.
2. Winnie the Pooh
Who doesn't love Winnie the Pooh? Kind, just a little dumb, cute, and has an interesting view on the world. I watched The New Adventures of Winnie the Pooh all the time as a kid, and into my early teens (I guess I should've stopped watching at that point, but it's just such an optimistic, nicely drawn, fun show, with great characters)
3. Spike Spiegel
The textbook definition of cool. Spike has a mysterious past, drives a cool spaceship, and tracks down criminals, but for all the wrong reasons ($$$$$) He has an attitude and is also skilled in hand-to-hand combat.
4. Severus Snape
Even though he was portrayed as 'the bad guy' in the first Harry Potter, from the moment I saw him, I was drawn to the character. Alan Rickman gives an excellent performance as the complicated, tortured, mysterious teacher of Hogwarts.
5. Stewie Griffin
Stewie is a lovable evil genius, yet still has the traits of a toddler, which makes him funny. He's got cool gadgets like a time machine, and will always chime in and offer funny commentary on a situation.