Most profitable use of Apex of Ascension?

Beside selling the whole map.

I've almost hit a jackpot with my temple-7 tier 3 rooms including Doryani's Institute, Wealth of the Vaal and Apex of Ascension. I want to run it, going to have a gem ready for it soon, but I have absolutely no specific unique to upgrade. So I'll be probably buying one and related vial and selling the result for profit...which leads me to the question, what would bring me most profit?

Whenever I get a tier 3 sac room, I always put in a belt on the off chance I get a Headhunter. it's never gonna happen though but I still do it anyway.