When I mention “elegant” I mean which class is more fancy. like if the toon were the high class society.
Some examples that comes to my mind:
Male Draenei anything. Their beautiful fridge-bodies are unmatched in grace.
Male gnome prot warr
Such elegance casting Ignore Pain all the time
No way XD haha
all that gnome screaming, much elegance
hehe 
The blood elf female from the TBC video. The one that murders the spirit snake thingamajig. She looks elegant at first glance.
I would say Nightborne arcane mage. Their voices are really pretty too.
Human Male Paladins are eminently elegant and fancy.
I dunno. Call me cray cray, but Nightborne female warriors
Zandalari anything.
Nelf mage.
Stop, my sides hurt now thanks! LOLOLOLOL!!!
Orc Arms Warrior. Finesse defined. Art in motion.
Troll anything. Aside from being the master race in WoW, we are also quite fancy. 
Blood Elf Mages. Any spec.
Void Elf or Nightborne anything, even our hunters bring an air of refinement…
Nightborne arcane mages and priest
Well, I would say any Elven race as mages, it’s their hole thing - Highborne usually were the ones that had access to study magic. The High Elves were a group entirely composed of Highborne, so in a way, while their entire society maintained their “grace” the mages certainly are still slightly more elegant than the rest.
The Nightborne mages with their heritage are great and Night Elven mages are quite literally the exiled Highborne that didn’t join the Legion nor joined Dath’Remar, so they still preserved their grace.
I mean.
Look at me.