I would use semi-sweet dark chocolate, pref coverture if you can get it nearby. You can either temper the chocolate and then cover the cheesecake, or if you're not familiar with tempering, simply microwave/melt the choco and add a glucose like corn syrup, brown rice syrup, invert sugar, etc to keep it glossy. If you have a small, flexible three-pronged fork you can use that to lower the ball into the chocolate, press down towards you so that it rolls in on itself and is covered completely, then lift it up and onto a silpat, lined pan/plate, or rack. If you don't have a fork, use any utensil that you are the most comfortable with, as that will give you the most control.
Just a note, if you are planning on freezing the cheesecake balls, I would recommend freezing them as is and then thawing out and dipping/glazing them a day or two before you serve. Otherwise, the chocolate could degrade due to moisture/humidity in your freezer, the thawing process, etc. and then it may have wild crystals all over it that will look funky (greyish almost like freezer burn, I suppose).