The most important questions is will you want to wear your wig in an updo or ponytail? If so you will want to choose a Full lace cap style.
There are many different style caps - the most common are the full lace cap with ear to ear stretch, the full lace cap with no stretch, front lace only cap meaning lace in the front only, full lace cap with thin skin in front and lace around entire perimeter of head.