Full-face 100%. I cannot tell you how many times I've gotten hit in the head/face at freeway speeds. When that happens I just thank god that I'm wearing a full face.
Items that hit my helmet include beetles, various sizes of rocks, some almost as large as the diameter of a half dollar, 6-8 inch long 2x4, 4-6 inch 4x4, exploding tires, etc etc.
Its great that you're thinking about it and you got a full face helmet. Now its time to think about your jacket, your gloves, and of equally importantance: motorcycle boots. Work boots and the like will not protect your ankles/feet in a crash.