I like legendary weapons with explosive damage added to them. I have found a 45 rifle (that I modded to a .308,,that thing will reach out and mess someone up), 10mm pistol and a shotgun all with it. The shotgun I found in Far Harbor and I don't remember on the other two. They are great ranged weapons, but not so much on close quarters due to the area effect damage they have and it will smack you as much as the enemies.
I also have a legendary shotgun with bleed damage that works pretty well. It even affects robots....I guess they bleed oil?
Then for some long distance damage I have a legendary missile launcher with a radiation effect on it that I have modded with a quad barrel and targeting computer. That last one is a must so you don't waste missiles. 4 shots with that usually takes down a milrelurk queen.