I agree with what has been said about Moore so far. Watchmen's greatest asset was its artwork.

How do you guys feel about From Hell though? I really quite enjoyed that one in my adolescence, I'm a stickler for conspiracies and all the occult stuff is very fun to me. I thought it was well made and had its own unique atmosphere going on, quite dense and dark.
I would love to read a novel that has something similar going on but haven't encountered anything of the sort so far