The Best Graphic Novels

I own Identity Crisis, Watchmen, Batman Year One and Killing Joke. I've read comic for a while but never read that many graphic novels. What are some other ones I should read? I'd prefer if they were only one volume

@tomzoid13: Batman The Long Halloween for sure. It has a follow up called Dark Victory thats also pretty awesome but its not necessary and they are both self contained stories. You should also check out Arkham Asylum: A serious House on a Serious Earth. To me its freaking mindblowing. Batman Hush is also pretty good though a bit divisive. Haha sorry that all I mentioned was Batman books. They are really the only single volume self contained novels I could think of off the top of my head, but trust me they are all amazing!

X-Men Worlds Apart for me.

If you like Cap? Captain America: The Man With No Face, and Captain America: Ultimate Winter Soldier Collection. Also, Kingdom Come was epic beyond description. Doctor Voodoo: Avenger of The Supernatural was amazing if you want a magic character. Also, it's not really a reflection of Batman at his best, but if you want a stunning story, check out "Arkham Asylum: A Serious House on Serious Earth". Really exceptional book that has all sorts of symbolic meanings and hidden references.