Anyone who said Fairy tail should go slap themselves. Dunno why people are saying FT is similar to OP, only similarity is the emphasis on Nakama, which exists in a lot of manga...
Full Metal Alchemist - Amazing Shounen, Amazing plot etc etc. One of the best Shounen Manga, you can often appraise other Shounen by comparing them to this.
Hunter x Hunter - Amazing, genre defining, adventurous, everything that the 'Big three' should be.
Death Note - Nice, thrilling, interesting, dramatic etc.
Tower of God - Amazing, great lore, can be unpredictable, great cast of characters. I don't even care as much whether the big three comes out nowadays, as long as ToG comes out it's all good. I was so happy when I found it, read it around 4 times already.

(actually a Manhwa)
Kingdom - Best historical manga I've ever read, stomps on the majority of manga out there, this and ToG are like my two great jewel finds, never thought that these two great pieces could exist, but they did.
Berserk - Golden Age Arc, nuff said. Though I wasn't a complete fan of everything else <_>.
Deadman Wonderland - Quite liked it, dark and gruesome, a bit confusing at times though, can't see it as a good manga just for a quick read.
AoT - It's pretty good, has a craze though.