I discovered how much I love attention to my nipples when I was in my twenties, 40 years later I still love it, it's one of my favorite things to do when I play. Mine are always erect, always sensitive, and always loving every kind of attention from extremely mild to pinching, twisting, and nipple clamps. I have come a few times with attention only to my nipples. More often they are a trigger for more regular orgasms. They are 1/2 inch long without stimulation, with stimulation they probably get to be three quarters of an inch high and close to half inch wide.
I adore finding a woman like Dallas Rain or Ms Athena who also have a great nipples and love attention. BUT, my favorite such experience of all time was several years ago, with a beautiful UTR Latina woman who was around for about 5 minutes before disappearing from the scene. Her nipples were even bigger than those of MsAthena, and she was most definitely orgasmic with nipple attention. We were clearly made for each other, unfortunately I only got to see her the once. But oh my, what an experience!! Lips, fingers, nipple clamps, doing nipple 69 on each other for probably 20 or 30 minutes, attaching our nipples each to the others with two sets of nipple clamps, keeping the nipple clamps in place when we moved to CFS. What a wonderful blizzard of sensations amongst very vocal moaning from both of us.....sigh.
Any other guys have nipples as an incredible erogenous zone!!