For now, it's hard to find which bounty campaign is the best and legit because most of the altcoin nowadays are scam.

But if you still want to why not check this one https://bitcointalk.org/index.php?topic=5164058.0
Since you are not looking for a signature campaign that one will be good you can join on their twitter and telegram or any from their list except for signature campaign.
I don't say they are the best since I don't know how legit they are but there are many bounty hunters joined in their campaign.