haha - okay, well from your list I'd have to say that One Piece tries the hardest to be funny (of course I've only seen a few episodes and never go into it - no offence)
Naruto can be pretty freakin funny at times too though.
Bleach made me smile.
Naruto made me laugh in the beginning... but then it wasn't so funny anymore after I started watching One Piece.
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I guess Yamato freaking out there was supposed to be funny, but for some reason I didn't laugh at it and didn't find it so funny at all. The humor from Naruto get fast old for me. It's the same thing over and over again imo. People freaking out. on the other hand, Luffy asking different creatures if they can poop doesn't really get old, ever.
The humor of One Piece is really consistent too. Fairy Tail makes me laugh sometimes too.