Let’s start off with the no-brainers: Swamp Thing - Alan Moore. The Punisher - Garth Ennis. Animal Man - Morrison. Doom Patrol - Morrison. Catwoman - Brubaker. JLA - Morrison. Starman - James Robinson. Golden Age Sandman - Matt Wagner/Steven T. Seagle. Supreme - Alan Moore. Stormwatch - Warren Ellis. Wildcats - Joe Casey. The Question - Denny O’Neill.
For Spider-Man, I would honestly go with Bendis. Stan Lee was first, of course, so obviously everything that came after must be compared to the original. But to me, Bendis’ Spider-Man is THE definitive take on the character, especially for our generation. As much as I enjoyed Paul Jenkins’ work and the stuff by JMS and Peter David, Bendis has written such an incredible volume of consistently great Spider-Man stories that I honestly don’t think that it’s fair to everyone else just based on number of issues. Bendis is the definitive Spider-Man writer.
For Captain America, I would also go with Brubaker. Steranko’s run was so short that I don’t think it would be right to call it “definitive” (especially because it was largely memorable due to his amazing art) and I don’t think I care for much of the old Captain America stories (other than Kirby’s art).
X-Men, I would go with Morrison. Even though Claremont was the one who revived them and basically saved Marvel back in the late '70s, I’m still going with Morrison. To me, “definitive” not only means that the body of work distilled everything that is great about the franchise, but also that the work holds up today and is worthy of being continually read by new readers and being reread by the rest of us. And, uh, sorry, but I don’t think I ever need to read The Dark Phoenix Saga ever again.
Daredevil, I would also go with Frank Miller. I think I enjoyed Bendis’ and Brubaker’s work more, and there are definitely aspects to Miller’s run that didn’t age well (too many expository story recaps). But that’s okay.
For Batman, I would also go with Frank Miller. Year One and DKR are still the definitive Batman stories. They’re both superbly crafted and pretty much distill everything there is about the Batman character.
Fantastic Four has to be Lee/Kirby. Their work on FF is the cornerstone the Marvel Universe is built on. 50 years later and people are still strip-mining those stories for ideas. Even though the dialogue may be a bit hokey, it’s still sincere and Kirby’s imagination was just awesome. The storytelling itself holds up and there’s no denying that so much else is dependent on the original Silver Age run. I will say that Mark Waid definitely wrote my FAVORITE Fantastic Four, though.
The Flash would be Geoff Johns for me. I’m probably biased because I really did not like Waid’s Flash comics. Johns’ Flash wasn’t perfect (he totally stumbled before the finish) but it’s still what I think of whenever I think of the character of the Flash. I also think Johns wrote the best Teen Titans (well, volumes 1, 2, and 4 are certainly definitive in my mind) even though I’m sure most people would go with Marv Wolfman. (Wolfman : Teen Titans :: Claremont : X-Men) And I’d say Johns wrote the definitive JSA, but I must admit I haven’t cared to read much other JSA other than the stuff he wrote before Identity Crisis.
Cable’s (yes, Rob Liefeld’s Cable) definitive writer has got to be Joe Casey. He and Ladronn did one of the unsung runs of late '90s superhero comics. Never been collected but it’s epic, powerful work. And all of us MvC2 players owe Casey for the Psimitar.
Iron Man is tough. I guess historically, most would say Michelinie/Layton. But I can’t read that stuff! It’s not up to my modern day standards and sensibilities. So I will go with Warren Ellis. Extremis is the definitive statement on the modern day Iron Man. Fraction has a good chance of supplanting Ellis in the future. Fraction’s definitely the definitive Iron Fist writer, although it’s not like he’s had much competition… But still.
Conan the Barbarian is tough, too. Roy Thomas did some awesome Conan comics back in the day, stuff that’s still much better than many of today’s fantasy comics. But Busiek’s Dark Horse stuff is really good, too. If anything, Thomas may get the nod because he did have a bigger body of work.
Green Arrow? Probably Mike Grell. I’ve only read bits and pieces of it, though. I really liked Kevin Smith’s GA (probably my favorite Kevin Smith comics ever) but due to the scope and ambitions of his work I doubt it would be right to pick it over Grell’s.
This is an interesting thread. Interested in seeing more comments.