...and though his work in the 21st century has nauseated me, most of what he did in the 80s and 90s was ground-breaking and supremely influential.
Wendy and Richard Pini of Elfquest fame were innovative and successful, so I would have to think their influence was felt.
The more I think about it, the worst this list is. I don't think Greg Land's art is influential at all, for example. He's just controversial after he was given the nick name "O face" due to his practice of using porn to draw from. And he hasn't been around long enough to have made an impact.
Miller's work on Wolverine, Daredevil, Batman, The Dark Knight Returns and Sin City as well as 300 proves to me he's had a far more impressive impact on the industry that a guy like Land, good or bad.