Classic Can't decide on class to keep as main for both PvE and PvP

Been sorta maining DK so far l and got him to cap and have been working on getting the legendary for unholy also got a fury warrior up to cap aswell but I'm unsure about what to use in PvP, I mainly do RBGs and haven't touched Arena ever I'm just unsure about what I wanna stick with. Been looking at locks and druid too but idk I think I might stick to melee but I don't know what class to stick to via /r/wow https://ift.tt/3rwwjHC