I spend 40 to refill stamina, often I spend 60 as well to do it twice.
The rest for tickets when there’s a hero I want/need.
Black market: never spend your gold, these rates are awful and gold is a big bottleneck. It costs 2 million to get an item to 50.
Honor points: I buy all the limited stuff, if I have spares I buy random accessories (unlimited)
Friendship: Vouchers, and spares buy hammers or xp pots.
Equipment: silver ore goes to gold (later you’ll have lots), otherwise buy rare martial spirits (300) to upgrade your SR gear.
Golden ore is too valuable for anything other than epic martial spirits (the thing that lets you raise maximum equipment level).