I have this ongoing debate that runs in my head, along the lines of Alan Moore or Grant Morrison? It turns out Gene Ha, who I think is the only artist to work on substantial projects with both writers, has thought about the differences and similarities too:

Alan sends out his script a few pages at a time so he can't rewrite after he's done, but when you read the whole thing it still comes out feeling like he tweaked the beginning after writing the ending. It's scary that anyone can do that with a first draft. Grant’s plots are beautifully constructed, but they don't have the structural perfection of a Bach concerto. He's more of a Beethoven or a Thelonious Monk. He takes the theme and runs with it.
In the end, I lean toward thinking that Moore's work suffers from his obsession with structural perfection -- even his most impressive stories end up feeling mechanical. Morrison, on the other hand, flirts with incoherence, but his best work (Doom Patrol, Flex Mentallo, New X-Men, the last JLA arc) moves me in a way that Watchmen never has.