Ok so i just read all the Tower of God chapters that are released up to now in 2 days and it just blew me away. I'm now looking for anything that's not on my lists but is similarily awesome. It doesn't have to be as good as TOG but it should have a solid storyline and likeable characters (at least the main ones should be likeable). Feel free to throw in anything that you remember as a really good reading experience.

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Errare humanum est, sed in errare perseverare diabolicum.

Thank you for the recommendations. Allthough i already read Fruits Basket, Love Com and Cat Street.
I'll definitely check out Death Note (I really don't know why i havn't read/watched this yet).
I started Mars a few months ago and it was'nt my piece of cake. I'm gonna check out the remaining two after my english exams tomorrow

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Errare humanum est, sed in errare perseverare diabolicum.

lovely everywhere
time stranger kyoko

Lol, I read the title and was going to suggest Tower of God. It's so ridiculously good. I don't think I've ever read any manga that was so well plot out like TOG.

Going along the webcomic vein, try:

Kiss Wood - Best part, it's completed. The art's a bit too... angular for my liking, but it has a pretty good storyline. Mildly bittersweet.
Cheese in the Trap - Fantastic character development. The story switches back between present and past a lot, which some readers find confusing.
Noblesse - Another extremely popular webcomic. Noblesse and TOG aren't very similar to each other than the fact that it's very engrossing.
Kubera - Fantasy adventure with scraps of romance. Throughout the story you can see some foreshadowing of what the story's going to become. I honestly feel that the current chapters aren't anywhere close to the climax.

Seconding Kiss Wood and Kubera

And is there anything specific you're looking for? Or anything you don't want to read? Because the criteria "solid storyline" and "likeable characters" can cover a really large variety of manga. There's really a lot of manga that I can rank as absolutely excellent just off the top of my head. And if you throw in just the really good manga into that list, well...

Anyway, I guess I'll just list some that are mildly action-y...
Billy Bat
Bokurano
Cesare
Claymore
Historie
Kekkaishi
Kimi no Knife
Liar Game
Monster
Murasakiiro no Qualia
Parasyte
Pluto (ok just read anything by Urasawa Naoki)
Ran to Haiiro no Sekai
Shoukoku no Altair
Shut Hell
Shuumatsu no Laughter
Spiral
Torikago no Tsugai
Ueki no Housoku
Vinland Saga
Zetsuen no Tempest
Zettai Karen Children

There's some really great slice-of-life out there too, so if you want that, I'll come back and list some of those later.

Please feel free to post dem slice-of-life ones as well! Thanks so far for your recommendations! I'll definitely check all of those out as far as my exams let me lol. Gonna try Kiss Wood and Kubera first probably. Cheese in the Trap is already on my Wish List. Your recommendation gave me the final push to finally start it.

EDIT: @ Suxinn: I generally read anyhing (OK i don't like tragedy that much but when it's well made it's fine as well). Im just looking for anything that really stands out from the rest. My standards went up drastically after reading Tower of God lol. It's just so well written in my opinion.

EDIT2: What i really hate are completely open or axed endings.

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Errare humanum est, sed in errare perseverare diabolicum.

What, nobody rec'd 3x3 Eyes?

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Is this me in a nutshell?
Pretty much.

Shingeki no Kyojin

You can either read the manga or watch the anime

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Angel Beats--best anime of the 2010 spring season

Recommending:
Kuroshitsuji
Pandora Hearts

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Drop by my fanfiction page! One Piece, Hetalia, Bleach, Harry Potter and more!
http://www.fanfiction.net/~stelraetnae

Kokou no Hito
Depends on your tastes, but that's my favorite manga.

For slice-of-lifes, you really can't go wrong with Aqua and its sequel Aria. It's really one of those mangas that help you notice all the beautiful, little things in life.

Also...
Barakamon
Blood Alone
Dusk Story - Tasogare Monogatari
Gin no Saji
Gisele Alain
Mushishi

Of course, as these are slice-of-life, it really doesn't have the super dense, conspiracy-ridden plot of TOG or any other action series in genre. Just a heads up.

Oh, and I completely forgot to mention Gunslinger Girl in my previous list. How did I do manage to do that? It's great.

Wow, so many recommendations! Thanks alot! It's going to take some time to go through all of them. If theres anything else that you feel is missing here feel free to post it

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Errare humanum est, sed in errare perseverare diabolicum.

Angel densetsu if you don't mind the art being bad, although after 10 or so chapters it grows on you for the type of manga it is, plus the art gets better in the later chapters

also recommend pretty much everything on my Faves list

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stupid photobucket, wanting $400/yr just to display your images