Virtually every coin to my name has come from slayer. I find slayer relaxing and it's just a constant flow of money into my account. Sure, the majority of this money is going to my increasingly large stock of fire runes, rune boot pile, seed stash and gem collection. The majority of my actual money, not wealth, comes from monster hunting, usually Dagannoth kings when I get dagannoth as a task and fancy a small change.