Watchmen
I love this movie. Its an almost perfect representation of the comic(if you exclude the ending) and the dark style of it makes it feel like a comic or cartoon. You really do get a feel for each character and realise that there are no good guys. The leaders and 'protectors' of the world are awfully selfish and oftentimes insensitive people. I think this movie came at Zack Snyder's golden age. He'd just done 300 and it was before he RUINED the DC movies (fight me). Truly a cornerstone of superhero movies and stories. MORE PEOPLE SHOULD TALK ABOUT THIS FILM!! Also I personally love the goofy Nixon prosthetic it adds character!