Raider Overhaul tweaks the faction that you battle on a pretty consistent basis around the Commonwealth. It's hard to go more than a few minutes without seeing a Raider.
With this popular mod installed on your PC, Raiders become a bit tougher. But that's not all. It also adds a ton of other items including masks, helmets, outfits, weapons and more.
The video below goes into detail about many of these changes and it's worth a look if you want to change the look and difficulty of the Raiders in your game.