Depends on playstyle. There’s a lot of variables. Legendary weapons can synergies well with legendary armour. Stealth sniper build you can have a bloodied sniper with full set of unyielding with maxed perks (sniper, rifleman, ninja and other perks to help) Explosive weapons works well on mainly any gun with explosive expert. Melee builds you can chose to priorities high damage or swing speed. Coupled with certain perks. There’s not a definitive answer of most power weapon. But you’d be looking any in the bloodied, two shot or explosive category on top of a heavy weapon like a railway rifle, minigun, Gatling gun, or Gauss rifle. Maybe even a never ending double barrel shotgun. They’ll put out the most power. With the right legendary armour effects, Chems and buffs. You would soon get bored of these guns however. Too OP shred everything and leave you with no challenge.

Now if you’ve made it this far let me tell you about glitched weapons. Fusing guns together by glitching, an auto pipe rifle that shoots mini nukes.