- you could start as a raider during the quest "When Freedom Calls" ( http://fallout.wikia.com/wiki/When_Freedom_Calls )

- conflict would be possible with other factions -> raid BoS airport base for power armors

- > raid RR because they killed raider gangs for harassing synths

- > capture the institute and use it as a base

- my ideea of implementing an Evil faction is to make it appear in a DLC , they come in force and destroy everything , and then u can rebuild , make alliances and fight against them ( or with them if u join )

- BUT it has to be done right ... with evil choices alot of murder and pillage , extortion and things like that .... if u do it any other way it will svck

raiders are junkies who has no leadership. They fight among themselves when deciding the leader. Unlike the gunners who has systems in place on deciding who becomes the leader of the group. So why people want to join the raiders is beyond me when you're still going to have to kill all of them anyway at any time your eyes intersects is silly.

Gunners are more organized and could have been used as a faction BUT with the lack of a karma system I'm not sure how this would work

They do actually have leaders in Fallout 4 there. Like 9 named NPC's that has their own gang and fight among eachother, and with everyone else. It is fleshed out in terminals and notes etc.

Yeah, Gunners would have been better choice as an "evil" faction to join.

Gunners would fit the best, and it could have been done with Maccready as the one introducing you. Would be a nice touch to make it abit more subtle.

They have unique NPC's in the raiders but they're still raiders. Nothing changes here really.

Raiders are Former Gunners.