Primary? Any primary weapon with the "Vorpal" perk....and then add a "Boss Damage" mod to it. Vorpal is an under appreciated perk that can make a noticeable difference in how much boss damage a primary weapon can do. You've been gone from the game for awhile, Breakneck (and all the other Pinnacle primaires) underwent major nerfs last summer....and will be infusion capped ("sunset") with the fall expansion in November. Armor 2.0 has also dropped since you last played. So don't just think in terms of weapons....the mods that go into your armor (especially from the Seasonal artificat) are extremely powerful. There are some STUPIDLY powerful builds that leverage synergies between weapon perks and armor perks that you might want to start experimenting with. "Oppressive Darkness" is a power-and-borderline-broken perk that makes void grenades (especially vortex grenades) into really nasty boss-melters. If you're a Solar Warlock, the combination of the solar melee mod and Sunbracers. If you pair it with warmind Cells you can construct builts that can basically let you spam solar grenades and warmind cell A0E damage if you equip weapons that do solar splash damage (like Sunshot). So you have a LOT of options to explore.