There's a lot of character designs that I love, because I love a lot of characters in video games.
The BEST one for me though...every time I think about my favorite designs, I always come back to Sweet Tooth's modern design from Twisted Metal:
I don't think there's any other character that I see where if his design is in a game, it makes me want to play that game. I already really like clowns, and Sweet Tooth to me has hands down the best design of any clown in video games. It's menacing, it stands out, and I just think it's damn cool.