Most common vandalism attacks (based on absolutely nothing scientific, just my recollection of the most common service calls I responded to as an installer):
Camera sprayed with lighter fluid and set on fire. The camera has to be mounted particularly low for this attack to be effective. I most often saw this in elevators and low hallways. I've seen this any number of times in housing projects.
Cameras hit with blunt instrument: baseball bat, hammer, rock. Mounting the camera about 10 to 12 feet from the ground usually lessened this threat. The higher the camera, the less force that could be applied. As Timothy points out, you will need some way of measuring impact. I guess you could get a radar gun, and figure the impact from the speed plus the weight of the object? I see a bunch of radar guns on Amazon for less than a hundred bucks, meant to measure the speed of baseball pitches. Maybe you could measure and see how much force an adversary can apply to a camera based on how high off the ground it is. Maybe someone already did that study.
Cameras hit with thrown objects. You'd have to be very bored, very patient, or have very good aim to try this kind of attack, but I've replaced cameras that had been hit with large rocks before.
Cameras pulled away from intended viewing area. A bullet or box camera can have a rope thrown around it, and, eventually, be ripped away from the wall or at least pointed elsewhere. A camera mounted low enough can be pulled off the wall by an adversary jumping up and grabbing it.
Gunfire. While I bet it would be fun to mount all your least favorite cameras on a wall and shoot them to bits with shotguns, I don't know how common a threat that is, and I don't think any camera would stand up very well to gunfire.
My feelings, though, is to mount the cameras at 9.5' or 10'. Too high to grab, too high to spray easily, and even if you could smack it with a baseball bat, the impact would be so light, the camera would not be damaged, and not too high as to create a viewing angle that's too steep to be useful. You could still throw a rock at it or something, I guess.