Hmmmm.... If it's my husband, I like to watch him undress and move around. He's lovely all over so I cannot pick one thing.
If it's a picture of someone else, I usually go straight to the overall mid section. I like that part of men best - belly, waist, thighs. Then then I do the sweep. I MIGHT go for the torso first. It just depends. If his hand is prominent in the pic, that could also get my attention. I do like viewing the family jewels first too. Again, I guess it depends on the body and my mood.