I second HunterXHunter - Gon and Killua are one of my favorite friend duos.

I also like Isaac and Miria from Baccano! / Baccano! (Novel) and Yun and Jing from 1/2 Prince / 1/2 Prince (Novel), but they're male + female friendships (and in 1/2 Prince, they don't really get important til 1/3 through the story).

+Anima

Legend of the Sun Knight

ONE PIECE

the only manga w/ bromance I liked.

"I'll shut your mouth~~~~~ with mine~~~"

二息歩行

i second santuary, not only are the male leads as close or closer then brothers but the story is fantastic. Hands down the best storyline i've ever encountered, all media combined. Comics, books, movies, tv, the story of santuary beats them all. It really works for your bromance genre.

...

Komatta Toki ni wa Hoshi ni Kike! is really great...but shounen ai ^^

Executive Committee I think fits. Unfortunately, it's not finished. The shounen-ai is pretty much the two characters putting it on.

Kyou Kara Ore Wa!!

The art isn't special, but it fits your request perfectly. The manga is about two guys transferring to a new high school. They seem to just suddenly decide to become delinquents (for basically no reason) upon. On their second meeting they end up fighting each other (for a reason, but it's a rather stupid one). Shortly thereafter they become the best buds (basically the way I make freinds lol) and proceed to embark on countless misadventures.

I doubt you will find a better bromance anywhere. Best of all there no shounen-ai or ect. There is some minor subplot romance, but the story is mainly focused on them and the trouble their constantly getting into.

(••) Future so bright...
( ••)>⌐■-■
(⌐■_■) Gotta wear shades.

Maybe Seishun Kouryakuhon?
Releases are pretty slow but I think it's great. 🙂

The average human starts spacing out after 10 minutes... so entertain me