most casters can be quite insane cannonically, on the other side more magicless classes seem to depend on magic swag or blessings.
I would say (not ranking them, just a rough idea):
-Demon Hunter-
Despite the name they are quite useful in killing many things, reading the illidan novel here’s a short list of their perks:
-healing factor, strong enough to heal from a skull gash in the matter of hours on it’s own
-heightened resilient, being shown to take hits from demons many times their size that would going by the books would have killed any normal mortal
-Spellcasting, yes they do use magic not only to augment themselves yet book specifically states that magic comes to some of them as easily as it does to demons themselves.
-Enchanted senses, not just referring to specteral sight, their hearing and touch is on steroids, vandal himself being able to sense the danger ‘in the air’ and dodge stuff coming from his back etc.
-Not to mention the fact that they are strong as ogres, able to shatter boulders with daggers WITHOUT specifically empowering themselves, while also being agile and fast as nightsabers.
-Death Knights-
QUITE sturdy, is able to utilise magic to a degree though less so than say a mage, it can still be QUITE dangerous, specially for the living, on top of that add saronite armor, rune swords, and a death charger and you have the wow version of the grim reaper.
-Dracthyrs-
Specifically -evokers-, being able to wield magics of all flights, though not AS potent as dragons, being able to combine different dragon magics is insane, in the war of the scaleborn, several evokers were able to bring ol’ razsageth down, while it took alexstrasza being blessed by other 4 aspects and given future sight to bring down vyranoth.
-Casters-
Kind of a slippery slope, caster strength is REALLY tied to individual differences, above 3 classes tends to be treated as: best of the best, in their own orders (illidari, dracthyr, ebon hold), so that wasn’t an issue for those, but for casters? Practically depending on their personal strength sky is the limit, specially for arcane. While void and fel seem to be more destructive.
As for shammies and dudus, their power is given by the world (spirit of the wilds/elements), so depending on how favoure dyou are, you can do some insane stuff! Like malfi holding the entire darkshore together for instance.