I actually went with painting.
Started with 4 painters and 4 sellers but quickly saw that did not work out as i wanted, so switched it over to 7 painters and 1 seller.
I sold all from the street gallery with 300% markup, and maybe 3-4 paintings per sim on plopsy.
Some of the best masterpieces has values of 12000 simeleons a piece, with 300% markup that was a good sale when that was picked up.
But i am actually really glad to see that it was another skill than painting that ended up being the most valueable.