I'm getting tired of series that focus on saccharine things like feelings & relationship drama & misunderstandings. I want something that's boy-boy or man-man with spicy stuff like crime drama, fighting, action, adventure, dungeon & dragons, zombie survival. Preferably something long as short one-shots are not worth getting invested into. I'll even take shounen & seinen series with heavy bromance.

Examples of stuff I've already read:

Fake: Focuses on two cops hunting down murderers. They hook up later.

Hunter x Hunter: The gayest shounen series I've ever read. The fighting goes on forever & the intershipping is endless.

Finder: A yaoi series about crime bosses, sabotage, betrayal, temporary truces, spying, etc.

GetBackers: Kinda like X-Men if it only had two characters that had the same profession as Gintama. Tight bromance shounen series.

Gensoumaden Saiyuki: A jousei series about 4 guys who bond while trying to save the world from demons.

Noblesse: A Korean shounen series about genetic enhancement & secret interspecies wars that go on without human knowing. Tight bromance.

I may be misunderstanding what you're looking for, so apologies in advance. Here are a few I believe may fit your request.

Apocalypse no Toride Summary is pretty self explanatory. Just a bunch of messed up youths against some nightmare-inducing zombies. Has a healthy dose of humour, bromance, and violence. Good example of mindless fun.

Out (MIZUTA Makoto) Main character has a history with gangs and just can't keep himself away from brutal fights, mostly due to his own temperament. Like other similar manga, there is a heavy emphasis on having each others' back, meaning bromances are inevitable.

Ares Unsure about this one but perhaps it's to your liking.

Imawa no Kuni no Alice A "play or die" situation featuring a trio of good friends.

Yu Yu Hakusho A classic. From the same author as Hunter Hunter,

Konjiki no Gash!! Typical shounen where main character and his partner share a strong bond.

This is the best trope in the world, imho. I get tired of every other trope out there, but not this one.

Hakata Tonkotsu Ramens (Novel) - The novel's ongoing, so I recommend trying out the anime adaptation.
Switch
Wild Adapter
Banana Fish
Karneval
Muhyo to Rouji no Mahouritsu Soudan Jimusho
Yakumo Tatsu
Full Ahead! Coco and its sequels/spin-offs.
Ake no Tobari
di(e)ce
B-Eyes has romance, but also a pretty solid bromance.
Saraiya Goyou
Ouja no Yuugi
Zenra Otoko to Shibainu Otoko - Keishichou Seikatsu Anzenbu Yuugeki Sousahan
Gin no Yuusha
Sougiya Riddle
Kemono Jihen
Makai Ouji - Devils and Realist
+Anima
Nanbaka, which also has a pretty nice anime adaptation.
Samurai Drive
Tekkon Kinkreet
Sennen Meikyuu no Nana Ouji
Servamp
Ilegenes and its sequel.
No. 6 (Novel) - The novel's far superior to the anime or manga, imo.
Himitsu
Vatican Kiseki Chousakan isn't scanlated, but it does have an anime adaptation.
Shirogane no Ou + sequel
Tactics

Vanitas no Shuki, ostensibly, but since this is the author of Pandora Hearts, I don't really trust the bromance not to be thrown out the window once the romance becomes more prominent.

Gangsta, maybe, but I haven't read any of the more recent chapters so I'm a bit dubious as to how the main duo have been getting along and how the romance(?) with the female lead is affecting the bromance. Ditto for Dogs - Bullets & Carnage and Owari no Seraph.

Seconding Apocalypse no Toride.

Will add to this list if/when I remember more.

Have you checked Worst, Crows, Clover? It's heavy on bromance, so much that , iirc, no women show up at all in the stories. Delinquent mangas, with street fights, gangs, and so on... It's the first mangas that came to mind. The action may not be what you want though, no martial arts BS, it's pure brawling.

Darn, can't believe I forgot to mention those! Btw, I think oneeyed meant Clover (TETSUHIRO Hirakawa), which does have romance, though it doesn't take centre stage.

Golden Kamuy! don't let the bara artstyle distract you from the fact that 90% of the male relationships are Wholesome and Bromantic. Tons of action, political drama and adventure to boot!

https://www.mangaupdates.com/series.html?id=26570
Sakamichi no Apollon
first thing that I thought of for 'bromance'; albeit slice of life rather than fantastical
a fluctuating volume of jazz music in the background is mandatory for this reading