ARK is a nice way of staking your coins. I have read on this forum, and elsewhere, that you get around 10 - 12% of your ARK in one year. So i think it is a pretty cool thing you can do, instead of just having them without staking them.
I mean, 10% yearly is even higher than some masternodes give.
I calculated my ARK return based on the last 19 weeks and my average annual return is 12.6720% compounded. This is higher than advertised because of fidelity bonus from my delegate (automatically given w/o me asking). I am pretty happy with this return.