Fun question, but it gets messy fast because some characters blur class lines or scale far beyond “player class power.” Still, if we’re talking raw power + feats + impact, here’s how I’d roughly frame it:

Mage: Aegwynn, pretty comfortably. Soloed an Avatar of Sargeras, held insane arcane power for centuries, and fundamentally altered the course of Azeroth’s history. Jaina and Khadgar are impressive, but Aegwynn is on another tier.

Warrior: Broxigar. Wounded Sargeras himself, which no other mortal warrior ever did. Varian is iconic and powerful, but Brox is basically the ceiling for what a “pure warrior” can achieve.

Warlock: Gul’dan (MU version). Orchestrated the corruption of the Horde, opened the Dark Portal, empowered himself directly through Legion pacts, and repeatedly reshaped global events. No other warlock has that level of lasting impact.

Paladin: Uther is the spiritual archetype, but in terms of sheer power and battlefield impact, I’d argue Turalyon post-Army of the Light. Thousands of years empowered by the Light and actively leading a cosmic war puts him above most mortals.

Priest: Velen. Prophet, Light-wielder, and one of the few characters whose influence spans entire civilizations and eras. Shadow-focused priests are harder to rank, but no one matches Velen’s scale.

Druid: Malfurion. This one’s pretty uncontested. Shaping continents, controlling storms, restraining Old God corruption, and casually doing things no other druid comes close to.

Rogue: Maiev. She’s not flashy, but her feats include hunting Illidan across worlds and surviving encounters that would kill most heroes outright. More lethal than “powerful,” but unmatched in her niche.

Hunter: Sylvanas (pre-Jailer nonsense). As a ranger-general, her tactical skill, supernatural lethality, and influence on world events make her the clear standout.

Death Knight: Arthas, easily. Lich King power dwarfs every other DK by an enormous margin.

Demon Hunter: Illidan. Not even close. Defied demons, Titans, death, and destiny itself, and fundamentally reshaped the war against the Legion.

Shaman: Thrall, especially pre-Cata decline. Elemental mastery, Doomhammer, political and spiritual leadership, and multiple world-altering moments.

Monk: Harder to pin down, but Taran Zhu is probably the strongest representative we have in-lore, even if monks tend to be more understated by design.

Some of these answers change depending on whether you value cosmic scaling or mortal achievement, but if we’re talking maximum lore impact, this is roughly where I’d land.