Push-ups give me a headache. I don't know if its the blood rushing to the head or the neck tension, but they are uncomfortable for me for reasons that have nothing to do with the actual excercise. Same thing for pull-ups, sit-ups or whatchamacallit.

Machines are comfortable while still maxing out my muscle capacity. They are the sole reason that I am now, after many years of repeatedly failing to start a weight regimen, enjoying gym excercise.

You are probably right in everything you said, since I know fuck all about fitness, but I know what I like.