Combined with the various perks in the base game and Nuka-World (Ace Operator). The goal of a sniper is the end the battle before it even begins without being seen and no weapon gives you that ability like this weapon. The Last Minute is unquestionably the best sniper rifle in the base game that you don't need RNG to get. So that'll be the frame of reference I am using here.

As for my experience, I primarily play as a stealthy sniper who has put in well over 500 hours into this game. Likewise, these weapons will all be judged with the 'ideal upgrades' not as they are found. That it is almost not even worth talking about. Why? Because the odds of running into any one of them is so low without hundreds of legendary farming time. Whereas a weapon such as an 'instigating Gauss Rifle' is not, thus will not appear on this list. So for example, something like the Overseer's Guardian will be eligible for this list because it is obtainable in every playthrough. For the sake of this post I will be including 'unique' and legendary weapons that are a guarantee spawn in every game.

Fallout 4 battle rifle