Hello! I’ve always been a melee player (except for boomkin) and this expansion I want to challenge myself into learning and playing ranged.
I’m looking at Mage, Hunter and Warlock as I think those classes have specs that most of the time are good.
My experience is around 2.1 in DK, Rogue, Warrior, Ret and Boomy.
Which class would you recommend and why? Which do you think is easier for an old man like myself?
Thanks a lot! 
All of these are very different with different playstyles and everything is subject to tuning and the rest of the meta.
However, BM is easily one of the easiest specs to pick up and learn and also one of the most fun specs to play. It doesn’t have an insanely high skill cap, but does have a ton of tools that are very effective. It’s also currently overtuned and one of, if not the trongest specs in the game!
I’d say give hunter a try!