When I was in high school, the exercise that we used to measure our strength was the bench press. Of course, the bench press is nowhere near a measure of overall body strength, but that was the weight lifting exercise that we were partial to.
Two of the best weight lifting exercises to measure overall body strength are the squat and the deadlift. Along with the bench press, squat and deadlift make up the three events in power lifting competitions.
I prefer squats over deadlift exercises because they work my calf muscles more, but both exercises work numerous muscles. Though they work some of the same muscles, these two exercises work the muscles differently, from different angles.