Doing what you like to do will also be more profitable than other things, all else being equal, because you'll be more motivated to put in the time and effort to keep your skills sharp and do a good job on the little details. Whether that means creative use of mesh for furnishings, or scripting new items, or drawing your own clothing textures, or whatever.
If there's a poorly filled niche you could possibly capture that market; you'd be working with a smaller market, of course, but you'd have fewer competitors than if you went for something that 100 other sellers are already doing and doing well. What would you want to buy, but have trouble finding?