One of the most refreshing aspects of Bendis taking over the Super books is that we've now got a Superman who is consistently funny again. Superman's sense of humor is a tricky balance that not every writer has managed to nail because he's often making jokes at the expense of hapless criminals completely out of their league. Thus far, Bendis has threaded that needle pretty well. Superman's humor was the secret ingredient of the Donner films that too many attempting to ape those films often forget-- Superman was constantly making jokes and was clearly having the time of his life playing the mild mannered goofball at the Daily Planet. Superman's also one of the first superheroes to break the fourth wall and acknowledge the audience, paving the way for Ambush Bug, She-Hulk and Deadpool years later. Jerry Seigel said it best when he explained that the key to Superman was that even though he had dedicated his entire life to defending truth and justice, he made sure to never take himself too seriously in the process.
In the right hands, Batman has the most cutting dry wits in the DCU, although that's clearly something he learned from the absolute master of the passive-aggressive sarcasm--Alfred Pennyworth. There's also a lot of comedy to be mined with the more self-serious Batman being so overly-sensitive about himself that he constantly feels the need to correct anyone who suggests that he pads his Bat-suit or one of his Bat-gadgets isn't perfect. The concept of Batman is so ridiculous, as most superheroes are, that I think he really shines when the humor isn't forgotten among all the misery, death, and sadness. Otherwise, Batman's just a sad rich kid with issues beating up the mentally ill.
One of the things that disappointed me the most about Dick Grayson on the Titans TV show was how utterly humorless he was, which, to be fair, was also true of his characterization in the classic Wolfman/Perez era. However, I think Dick works best when he's cracking jokes non-stop while punching badguys with a big smile on his face. Hopefully, they'll course correct in the second season, particularly after seeing how successful Doom Patrol was at balancing the humor and darkness. I'm not even going to get into the mess that comics's Dick is currently mired in
Wonder Woman is a bit too serious for my tastes, along with Aquaman, which is likely why I've never warmed to either of them enough to regularly follow their titles for any extended period of time. There's certainly been some great comedy mined from Diana's early experiences in Man's World, such as Johns's oft recycled ice cream joke, but few writers have managed to give Wonder Woman much of a sense of humor in the modern day.
The same has unfortunately been true of Aquaman in the comics, although the Brave & the Bold cartoon and Jason Mamoa have certainly found ways of making the character funny. My guess is being saddled with being the father of a dead baby for decades had a lot to do with that, which is very likely one of the main reasons Geoff Johns retconned that away as soon as he could in the New 52. Not many guys are going to be cracking a lot of jokes with a murdered infant son haunting them forever.
The Flash has generally managed to remain such a light-hearted superhero, despite all the various tragedies creators have thrown at them, and each speedsters respective sense of humor has been a key factor in that. Whether it's the dad jokes of Jay Garrick, the nerdy quips of Barry Allen, the everyman zingers of Wally West, or the ADHD goofiness of Bart Allen, The Flash is almost always a funny character.
Same goes for most of the various Green Lanterns. While Alan Scott was the straight man to the comedic Doiby Dickles, Hal Jordan was constantly creating goofy constructs for no other reason other than making himself laugh like trapping a purse snatcher in a giant green purse, and this was carried over to later GLs like Guy Gardner and Kyle Rayner. Even though John Stewart has been stuck being the more serious due to his own personal tragedies of being widowed and more, he was actually pretty funny in the beginning, like "accidentally" putting a racist politician in blackface.
Martian Manhunter's bemused, sometimes exasperated, but worldly sense of humor was one of the delights of the Bwa-Ha-Ha era of the League. It's a shame that not enough writers show this side of J'Onn anymore.
What about you? Which characters in the DCU have your favorite sense of humor?