I loved Naruto, not a single comedic moment in my years of reading got me to deviate from a straight face. Even in my most immature middle school days.
The unintentional stuff is what got me in Naruto, mostly Obito scenes. War arc had me cracking tf up. Coolest guy chapter had me on the floor. And there was also the scene where Kishi drew a black page with text that said "I don't care anymore" which had me dying. On a reread post Danzo fight, when Kakashi was gonna use Kamui and Obito told Kakashi to halt because "it won't work on him" like it wasn't the one thing that could work on him π, I always imagine him sweating bricks behind the mask hoping Kakashi buys his bluff.
Same deal with Bleach. The intended comedy scenes are extremely lame but the unintentional stuff is hilarious to me.
GTO is one of my favourite mangas of all time and I don't think it's all that funny. Really it's just Gintama all on it's own with a massive gap, then One Piece.