Quenya has an entire backstory and narrative that went from vanilla to Legion. Then the RP guild I was in kind of fizzled.
Her look hasn’t really changed since Legion, except for the tabard. and the wrist. Her hair does change. When I get a haircut, so does she 
This. I try different looks that fit the race-class theme. I think my only character that doesn’t follow that is an evoker I made with Zandalari theme. I like to think he decided to go live in Zandalar to learn the culture and stuff, so he dresses Zandalari armor.
Point 1, incorporating point 2 pretty much to a tee.
its a mix of things. i try to blend cute girly stuff (my personal prefrence) with class aesthetics, like my casters have more casual attire like scarves and backpacks, whereas my melee fighters will wear stuff like head bands and wrist wraps, that kinda thing. they all wear skirts though, no exceptions lol
If I think my transmog meshes together well, then I like it. I’ve actually been using the one I have now pretty regularly for years. I’ll change it up occasionally, but I always go back to my favorite. It’s about what’s appealing to me above all else. I also like to throw a bunch of pieces together from different sources. It’s a small way to challenge myself. I also try to make sure my warband (my main 4 I’m focusing on) all have different colored outfits. Another challenge for me. If someone else likes what they see, then that’s cool I guess, but my own satisfaction is my only concern.
I vacillate between attempting to mimic D3 Crusader look, an armor “appropriate” for the current patch, and skin mogs and a Barbaradin ethos.
You know that blizz said back then that they wished they never made rogue class
Hell if I know.
I go all over the place depending on a lot of things. If I like a leveling or open world set, I’ll roll with that for a while. And sometimes I just want to look like a Spartan.
Generally, I go for a look that matches the character I’m portraying when rping; at least as close as I can, as that is harder to do for some compared to others. As an example, I currently portray a civilian on one of my Night Elf Warriors. Her current mog uses a shirt, the original chest from the racial start, boots from one of the trading post pirate sets, and a set of legs that I thought looked closest to normal pants, since the only armor type with actual normal looking pants is cloth.
I tend to prefer more practical, down to earth looks. I’m not a big fan of oversized armor pieces and weaponry. In most cases I tend to hide shoulders on cloth wearing characters partially for that reason.
I’m so boring, I don’t even qualify as the main character in my own life. No elaborate backstory or rich details. Lazy and Simple aesthetics.
Grease Monkey / Chop Shop + Goblin Calendar.
Security Conskulltant
Mostly based on my mood. Sometimes it’s fun to go full on power ranger mode and throw on some t5 or go bananas and throw on t1. Other times it’s “I don’t feel like being so full of light today” and I throw on DK based armor. It’s pretty haphazard.
I suppose you could say I make my character mogs part of the entire package. First and foremost, Red is my favorite color. My BDK here had a less dark red outfit that was almost unchanged from Legion through DF (only swapped out a sword and belt). When farmed up Varruth’s Guillotine it was to sweet to sell so I got armor to go with it (SL was good for something). For a ground mount I use the Crimson Deathcharger (perfect match). My flying mount of choice is the Bloodbathed Frostbrood Vanquisher - a hint of red and perfect for a DK (the class mount was a novelty that wore out in about three days). All other alts are similarly paired.
It changes every week
I’ll often mog for a current holiday though.
my guild has weekly themes, which i enjoy, so that determines my fit
My main runs around in his underwear as he has given up.
Mostly this. Sometimes I go with what looks swank.
For me, it’s mostly what looks cool. Which naturally takes race into account. I generally try to make it feel shaman-y as well.
I typically find a helm or shoulders I like and build around it. I try to avoid full sets.
My choices are based solely on what looks hot.
My aesthetics revolve around magitech, or the renowned Technomancer.
Modern Titan Technology and the Arcane make for an extremely lethal weapon. 