In the broadest possible terms - a pve godroll primary will nearly exclusively involve a reload time reduction perk and a damage increase perk. The current favourites are usually feeding frenzy and rampage, and more recently, Frenzy. Masterwork and barrel perks depend on weapon type, ie short range weapons should have a range increase or recoil reduction, handling, etc. Secondary and heavy preferably a perk to increase reserves and ideal perks vary more widely depending on weapon type. -pvp godroll depend more heavily on playstyle than pve. Range and reload speed or handling/ ready speed usually more important that damage increasing perks due to the short duration of damage increase perks.