Not sure ho serious this is but my rule of thumb that I learned when they first came out was 12/15-35 for Gusgen
next would be CN or GC (tho GC is dead for some reason idk why maybe too many ppl kept falling) till lateish 50s or early 60s then its Boston Ob GoV till you're ready for abyssea.

I dont make a habit of GoV'ing since Inventory is a issue for me >.>