I think it depends on the effort you want to put in to earn benefits. Bounty campaigns give you rewards for the tasks you give for free. But to give a substantive amount of coin, more tasks are required and usually takes a long time to receive the rewards. And there is a risk you won't even receive at all. For trading, you must first know the ins and outs of the process as you will be shelling out funds to trade coins. If you have the skills to predict market prices, trading will give you great returns at a short time.
I recommend that you join bounty to receive free coins and use these coins to trade. Just like I did.