I've never really been into buying the monthly comics, probably because it's not such a big market in DK...but I've taken every opportunity to get them at the library!
Watchmen, Ultimate Spiderman, Uncanny X-men, Transmetropolitan, Red Son, Superman Seasons (I think that's the name), Kingdom Come and everything else I could get my hands on. And Sandman, of course! Much love to Gaiman, I own all of his books (except the graphic novels, they are nowhere to be gotten...)
Manga...hmm!
Naruto, One-Piece, Hellsing, Death Note, Gravitation, Vampire Knight, the Queen's Knight, Basara, Othello, Emma, The Demon Ororon, Nana, Kashimashi, Catwalk, World of the S&M, The Wallflower, Samurai Deeper Kyo, INVU, Her Majesty's Dog, Paris, D.N.Angel, Hack, Bleach, Chobits, Chrono Crusade, Shaman King, Full Metal Alchemist, Higurashi no Naku koro ni, Love Hina, Akira, Ghost in the Shell, Paradise Kiss, Princess Ai, Cardcaptor Sakura, Fruits Basket, Ranma ½, XxxHolic...and a bunch more. Impossible to remember all the names. A lot of them are Korean, a few German (we buy most of our manga in Germany, they have a much better selection!)
Phew!
~Moi