What is currently the best build in fallout 76 for killing big bosses like scorch beast queen and earl Williams?

Low-health VATS commando, especially if the weapon is a quad railway rifle. And especially especially if they stack Endagerol Syringers, and all available consumable buffs.

I'm guessing he used endangerol first. My Vampires auto axe melts most bosses currently. We will see how it fares post update.

You will get a bunch of people telling you that you have to be a Bloodied build. However every time I do the Earle event, it’s me and my Quad Crit special Railway rifle doing almost ALL the work. I’m a luck-heavy full health commando. I’m almost unkillable and end game bosses do not like me.