Myself - Revington Duchaine, Tabaxi battlemaster. I’m I. My home woods, my trust bow drawn, an arrow pointed towards the viewer. Over my right shoulder you can see the other members of my party, looking on awestruck at my heroism and competence.

Ace: "A painting, you say? Oh, I know! Paint me juggling flaming swords while riding a unicycle across a tightrope! And make sure there's a bunch of chickens in the background wearing tiny crowns—because why not? Oh! And throw in a flying pie or two for good measure! The court needs more chaos, don’t you think?"

Tethys: most likely the night sky, maybe even with the star signs hinted at, so it’s easier to show them to team. Or a portrait of her pet, Pips. (Goody 2 shoe, star Druid, odyssey of the dragonlords)

My character would definitely ask for either their favorite sheep or their favorite spot in the woods to be painted

I’m in a couple campaigns at the moment. The Werewolf would commission a painting of her family, as would the Drow and the human spy/ranger. The Space Scum however would probably ask for a painting of her Void Prince Demon boyfriend and her demon cat.

My trickery cleric would ask for a portrait of the painter himself. And just leave with it, not explaining anything.