I've been struggling with the decision myself between the S7 and S7 edge, but not for the durability. However, I feel that the edge screen is more vulnerable to damage if left unprotected. Being that the two devices sport glass screens and backs, the likelihood of a crack when dropped on a hard surface depends on the height and angle. Because the curve wraps around the sides of the device, there is more screen exposed.
Whichever you one you go with, find a case that you like (Spigen makes nice cases) and put it on your device. Insurance is a must if you insist on going without a case.