Wow is a game. The Devs work hard to balance all the races and classes. But Lets do a "What If " just for fun.
What If: We considered all the Wow Races and Classes to actually exist In Real Life without being balanced. Which class do you think would be the Mightiest Race/Class in the Entire World?
And on second thought.
What IF: The Race/Classes were not Balanced In-game? Who would be Top dog?
An Elf Warlock would be the most powerful. Maybe Undead.
Elves arenât countered by Light/Holy like Undead are. But easier to kill by conventional methods.
Warlocks tap into life and convert it to power, Elves have a lot of that.
Theyâre ranged.
They summon demons.
They can cause plagues.
DK for similar reasons.
But ultimately a DK would probably just be incinerated by a Warlock before they get close. Youâre not just shrugging off an IRL Fel Guard.
The only other potential IMO is Rogue. But thatâs just for the cheesy âsneak up and stab you = deadâ answer. Depends how invisibility would work IRL. It would need to cloak scent and sound to sneak past a Demon.
While I do love warlocks. I think a druid would actually be mega op. I mean if druids are anything like end game DnD druids.
in universe, mages are stupidly powerful.
In real life though, my vote goes to warlocks, demon hunters, and death knights.
I think hunter with a rifle would be OP, because a bullet in the head kills most of the things.
If the game was based on real life, the band âFlock of sea gullsâ wouldâve been named âflock of Druidsâ effectively altering the course of the 80âsâŚnow that POWER! 
I picture a Rogue in real world as a Ninja on steroids. So quite powerful. And even if your philosophy allows the existence of Demons, I think the chance of being unstealthed by a Demon IRL is very, very tiny. 
Only warriors , priests and hunters exists
Bit ethnocentric, yes?
Demon Hunters and Death Knights aside, every other class is named for an occupation in our real world.
[Edit - Oh, you did include Hunter. I donât know how I missed that. Leaving my commentary intact.] But the biggie that you overlook is Hunter. âBut not with animals!â you may protest. Au contraire - people still breed, train and employ hunting dogs all the time. A RL Hunter, with a RL rifle, and RL dogs is a formidable opponent.
Of metaphysical classes, the oldest (dating from the stone age) is probably Shaman - a professional caste of Finno-Siberian tribal peoples, which combines religious functions with folk medicine and something an awful lot like what we call psychotherapy.
We have written records of established, organized, regulated priesthoods going back as far as we have writing - roughly 6,000 years (ancient Egypt, as a culture, is astoundingly old). Contemporary religion demonstrably derives from these practices.
Monks are real, and an actual Kung Fu adept really can mess you up, bare handed. To what extent Chi / Qi / Ki is real, and to what extent it is woo is open to debate. The effectiveness of a flip kick to the head is less so.
Iffier are Mage and Warlock, although the distinction has been made since at least the time of Homer (Iron Age Europe, approximately 500 BC) between theurgia, or socially sanctioned, educated, ceremonial magic, and goetia, superstitious, disreputable traffic in the Black Arts. The distinction remained current into the Early Modern period, and just for one notorious example, Aliester Crowley (1875 - 1947) is known to have employed both up through the Second World War.
Now, occultism is full of flim-flam, but regardless of its effectiveness, serious people have and do seriously practice it. Jack Parsons, a late protege of Crowley, was also a founding scientist and aerospace engineer at the Jet Propulsion Laboratory in Pasadena, CA. (Parsonsâ magical work is a matter of public record, and led to his expulsion from the program in 1944.)
So wizards and warlocks? Yep - actually a thing.
Paladins havenât been around since the collapse of the Carolingian Dynasty. In troubadoursâ tales, they were twelve knightly companions of Charlemagne, who did noble deeds along the same general lines as the wholly fictional King Arthur and his Knights of the Round Table. In actual history, paladins were court officials and magistrates of the Merovingian and Carolingian Frankish kingdoms of the early Middle Ages (about 600-900 AD). They were as effective as any trained, mounted, armored man swinging a sharp, tempered length of steel. That said, they lost the Battle of Ronceveaux, and the Moors were not fully expelled from the Iberian Peninsula until the Fifteenth Century. But yes - there really were paladins.
We know next to nothing about ancient Druids, because all our written records of them are from hostile sources - Roman historians, and Christian monks. But beginning with the Romantic Movement from roughly the latter half of the Eighteenth Century, we have seen various attempts, more or less imaginative but sincere in intent, at revivalist practice.
The best established, and most respectable, is the Order of Bards, Ovates and Druids, which can trace itâs origins to the Gorsedd Cymru, formerly the Gorsedd Beirdd Ynys Prydain, a Welsh revivalist order dating to 1792. Queen Elizabeth II, while still princess and heir presumptive to King George VI, was initiated as an honorary Ovate in 1946. Her honorary membership was rescinded 60 years later, when bylaws of the Gorsedd required its members to be at least marginally fluent in Welsh, which Her Maj sadly is not. Nothing in the bylaws about being able to turn into a bear.
If we interpret Warrior as âsoldierâ, in a modern, military sense, they probably win this shin-kicking contest from sheer material and governmental support, especially if we are talking units. Even individually, Iâd bet on an equipped special forces commando against a hunter or martial artist. That said, individual expertise varies.
There is a long history of fiction around all these, most particularly distortive in regards to magic, or what actual practitioners expect to achieve versus Hollywood fantasy. But they are all real things, DKs and DHs aside.