To speak first of all - I totally exclude both Ner'zhul and Gul'dan from the poll - if not taken aback, they'd easily smash all others to dust, even all together. It is pointless to compare a most powerful mortal warlock in history, who could raise damn islands from seafloor, create volcanos or wipe an entire army with a single spell, killing his foes by thousands; with some brute with an axe. Or the gretest shaman on Draenor, who, armed with powerful artefects, was able to rip a PLANET (!) apart.
Well, the poll is about - fair, poweful warriors on the arena, with their suits and weapons of choice, if they have gadjets or minor magic, or phychic attacks, it's all with them, as well as preferred gear. So, this are conditions. Along with actual Warlords, Thrall as gladiator and Garrosh without any Y'shaarj stuff are included.