For me the highest profit is signature since with airdrops you use a lot of time and u gamble if it will ever get some value.
Bounty is worthed way to do, this is simple, just join and follow their rules, and make sure you choose the bounties that fit to your rank (if that was signature bounty).
Rules of the bounty is the number one, if you dont read it carefully and you didn't get for the bounty stake, then you just waste your time for nothing
You can see my signature, these one is simple one, but you must to stay read the rules