I'd include Wallace Wood in that company, too, though he's in the Eisner Hall of Fame – Wood died before they started giving out the awards. Incidentally, Wood was also a big influence on Nowlan. His collaboration with Alan Moore on Jack B. Quick has clear ties to the classic EC comics sensibility.
(For more on Moore, I shamelessly refer you to The Best Christmas Comics to Give to Collectors and Six Classics of Comic Book Theory.)
What's remarkable about Kevin Nowlan are two seemingly contradictory facts: first, he has a very distinctive style – his attention to detail, the angular features of his characters, and the faint cross-hatching along his shadows are always dead giveaways.
Second, he's done so much, and such varied, work over the years that it's surprising that it hasn't been noticed more often. While going through his credits, I found myself going "Kevin Nowlan did that, too? ... Oh yeah..." more than once. Since he's rarely attached to a project for long, it's the memorable one-shots, like Superman/Aliens and Batman: Black and White, that stick out.