I'm an older guy, lifting for almost 20 years. Knee joints trouble me the most. And from my personal experience - heavy weight and low volume wears the joints much less than higher volume / less weight...
For instance, I can do a heavy 1rm squat (after warm-ups) and my knees won't bother me at all, and on the other hand if I do Tabatha's on the elipticall (which is much less force, but more of it), my knees are shot...
So, my vote is definately heavy weights / less reps / less overall volume...