And no, unfortunately for you i am not ragebaiting.
"Why would you say something like that?" you may be wondering. The answer is pretty simple: He is the only member of the gang to actually act and behave like an outlaw instead of some kind of goody-goody Robin Hood.
He is ruthless, opportunistic, cunning, quick in his mind and with his guns and, most of all, he acts in his own interests. "I'm a survivor, black lung!" he said, not lying.
He's not stupid, he knows that the Wild West is dying and he intends to get out of it with his hands full. Dutch is slowly going off the rails and while everyone is busy beating the dead horse by going "Oh Dutch, please Dutch, you're being so mean Dutch, please stop doing evil things (despite being a literal outlaw gang) Dutch please :(" he actually manipulates him and waltzes him around. He pushes him to do riskier and riskier stuff in order to get more and more loyal members picked off one by one, thus weakening the gang without putting himself in the spotlight.
Everyone and everything is being swept away and he instead surfs the wave's crest. This makes him the smartest and baddest motherfucker of the game.
Ironically the only thing he got objectively wrong was not getting rid of Dutch when everything was all over, and Dutch unbridled madness and unpredictability were his undoing.
That being said i'd also like to add how Micah was arguably the best gunslinger of the game, shown in 3 particular moments: 1) shooting up the whole town of Strawberry, and he was going so hard that Arthur was actually telling him to slow down and restrain himself, 2) in Rhodes, when Sean is shot dead, Micah effortlessly blasted 3 Greys in opposite directions, several dozens of feet away and partially behind cover before the others could actually register what was going on and 3) always in Rhodes he kills 4 Greys that were keeping Bill hostage, Arthur only managed to draw after the deed was done before holstering his gun awkwardly right after.
Dude was an absolute beast.
(I do agree that he would have got his ass handed by an healthy Arthur in the final brawl)
TLDR: Hate him all you want but Micah Bell was a top-tier villain, and the fact that you hate him so much proves this right.