The issue isn't whether swapping subframes is simple... it's just less simple than swapping diffs. The OP wanted to know what was the least time/effort to swap diffs, diff only or entire subframe. As was abundantly demonstrated, there's a lot more involved in swapping subframes CORRECTLY than just swapping diffs.

FWIW, I just discovered that the exhaust hanger in a 2000 subframe is in a different location than the hanger from my 1993. I just did the sub-frame swap, but I was doing bushings and brake caliper swap at the same time, so the alignemnt and brake bleed were going to happen anyway. I've also "heard" that the geometry of the newer subframe and A-arms (NB) was better than the older ones (NA).