I say doesn't matter what kind, white blue green legendary, because as you know in pvp that's not iron banner, weapons are all balanced. Having a blue or purple would give you some additional perks. But a white auto rifle would indeed be a cheap quick fix

I recommend an auto rifle, doesn't matter what kind, with some decent stability. If you're good at pve then shooting people in the face is nothin new to you. Move slowly, watch your radar, and wait for your chance. You can only be cheesed with a shotgun if you get into their personal space :) hope this helps not trying to state the obvious