I second Berserk. It's in the mature category, with plenty of violence/the occasional [censored] scene, so it's not for everyone. But the story and the art... wow.
Gundam Eclipse recommended 20th century boys, I agree. Even if it was without any of the actual pictures, the story alone would make me read it.
Out of the popular weekly mangas, I would say One Piece is the best, and it's one of my overall favourites. In my opinion it's leagues above Naruto, Bleach, Fairy Tail, etc. (I read those too, but One Piece is the only one I really look forward to reading each week).
Full Metal Alchemist... if I could live in any fantasy world, it would be the one from FMA. Definitely recommended (the Full Metal Alchemist: Brotherhood anime is also great, follows the manga to a T, and is one of those rare animes where I thought all the voices fit the characters just right. Wait... never mind, there was that terrible terrible panda voice...)
Dragon Ball is also a great classic to read
. Somewhat silly, and not exactly the best of stories, but it did essentially start the whole shounen genre as we know it today...
done reading FMA:B and i've been reading naruto, fairy tail and khr, don't like bleach and one piece though.
i'm currently reading psyren, found it while browsing yesterday, looks kinda good. i'll add berserk, 20th century boys, higurashi and what naglaro00 recommends.
dragonball, don't wanna read this, i grew up with this always on the television.
thanks for the recommendations
Yes, definitely read Gantz, it's epic. There's plenty of strong violence and a fair bit of nudity and sex but if you don't mind it check it out. What intrigues me the most about it is the story and character development, one of the best I've seen in any story.
Yotsuba&! (the best manga ever IMO)
Bokurano (if you liked Evangelion, read it. DO NOT look up any plot summaries because it will ruin a major plot point)
Kodomo no Jikan
Jojo's Bizarre Adventure (Be warned, there's over 900 chapters and the translations for part 4 are kind of bad and part 7's (current) are slow)
Hoshi no Samidare