I like having this conversation from time to time. Which class is strongest in terms of lore, ie what they can do in the story(not gameplay). I think it would be this (descending order)
-warrior/hunter/rogue: all about equal, regular soldiers/mercs. Power comes from training and gear.
-Monk/priest: I’d say monk is stronger than the soldier classes due to more training and some magic/chi stuff. And a priest has the light I guess
-paladin/shaman/Druid: these guys have been shown to be seriously powerful, having achieved incredible feats by themselves. Even some of the weakest are still pretty strong.
-mage: some of the strongest people in Azeroth are mages but they have put in a lot of work to get their. I think a good mage would wipe the floor with most classes lorewise.
-DK/DH: these are hero classes that can singlehandedly wipe out regiments and control immense power with both magic and martial prowess.
-warlock: basically 70% of azeroth’s problems have been due to a warlock opening some portal or raining death on people.
Warlocks. The magic they use is boundless and all consuming. Any magic that comes into contact with Fel either explodes or is consumed to make more Fel. Warlocks have destroyed whole worlds. Fel magic has created objects that are so powerful they have woven themselves into the fabric of reality itself, the Scepter of Sargeras.
Unless of course they get ganked from surprise by a rogue or assassin. See how much casting they do from stunlock. AU Garona nailed Khadgar on Draenor.
Really strongest is always subjective the two hero classes are very strong mage and warlock are likely stringest casters but that is all on the individual over the class.
I think casters take the cake for this one. Warlock, (Shadow) Priests and Mages literally harness some of the most chaotic energies in the universe. It comes up a lot that dabbling in these magics can come as a massive cost. Fel, Void and Arcane are all very volatile especially when wielded by a competent scholar. No one suspects the nerds.
Hero Chin probably could have taken out Gul’dan if the latter didn’t have the whole freaking Legion at his side. Circumstances are a large part of cases.
Which is why the strongest of all aren’t a “class” in game, but rather the goblin and gnome techies who have created things like nuclear weapons and world shrinking devices.
Whichever class is represented by each xpacs end tier raid bosses. It’s more about which character is important as an antagonist or protagonist and whichever class they represent is as powerful as the story needs. There is no rock/paper/scissors from a lore perspective.