There is a reason Alan Moore does not attach his name to the movie versions of his books.
League of Extraordinary Gentleman is unwatchable, whereas the books are very good. God the movie is just an abortion though
From Hell was given some weird super natural element (amongst other changes and additions), complete joke.
Watchmen... Just should have never been made into a movie. It was explicitly made to showcase what the comic book medium could do, and was written to exploit the medium to its fullest (the ability to flip back pages, the combination of written prose and the typically graphic panels, the interweaving story lines with the ship, etc...). Snyder did a valiant job with the movie (I personally did not like it, and I hated what they did to Manhattan) but as I said, it should have never been a movie to begin with.
V for Vendetta was passable until they went all Hollywood on the ending.
I'm really not sure why Hollywood wants to remake Moores books given how much they change them from the source material.
I find Brian K Vaughn a compelling writer and would recommend just about anything he has done (Of note ate Y: The Last Man, Pride of Baghdad, Runaways, and his current series Saga)