Edward Richtofen from Nazi Zombies in Call of Duty, it's fun to continually replay those levels just to hear those German innuendos and puns
Lloyd Irving from Tales of Symphonia because he's for one adorable and is the BEST at dual-katana swordplay EVER, not to mention tries to stay bright in even some of the worst situations.
Sonic the Hedgehog - Despite years and years of terrible games after Sonic Adventure 2, I still enjoy playing games with him in 'em. I somehow find some joy in newer titles like Sonic Rush 1/2 and Sonic Unleashed and especially now with Sonic Generations which brings back sooooo many of the old levels in awesome quality.
Sam - From the games Sam and Max, the "brains" of the operations and always has some sort of pun or innuendo humor to say, makes me laugh everytime I replay the point-and-click games
. I just wish there were more of them now ;A;
Laharl - Disgaea's original main character. I think the way they made the character develop while the story progressed about being more accepting of things he used to hate makes the story a lot more desirable. Supporting characters like Etna and Flonne make it even more fun to replay and the massively insane amount of levels you can upgrade your characters to in the four digit range is also pretty unique and at the same time sometimes unforgiving which makes the replay value go up!