Starting off at 160s - 75fg Per portal or 200fg for all 3.
170s are 80fg Per or 220 fg for all 3
180s are 90 fg or 250fg for all 3
187s are 100fg per portal or 280 fg for all 3.
Uber bossing - 30fg (I average around 3 legendaries per kill from her at any tier. They fixed the loot drops)
If you want a Sarisel run (Untainted), add 10fg to the price of per portal. It'll be up to you to survive. I do 187 Untainted runs in 4 min solo, so it'll be about 8-10 min for the full run.
Based on the coding of this game - Tier 161 = best for loot. You can't get mods to roll higher and you remove t9 possibilities. You can see the coding for yourself if you unpack your umbra.pak file.
Anything higher, the only benefit is to unlock it, more legendaries drop due to increased quantity, gems are WAY more plentiful (Average about 2 Genesis stones per run, these are very important for crafting high end gear), and the exp is far better.
I will also field any questions if you decide to join the d2jsp discord while I level / carry you.