I love erotic photography. Perhaps the most erotic photgraph for me was a famous Playboy one in the '70's of a girl's nipple being pulled by a beautifully manicured female thumb and forefinger. I spent a lot of time with that photo.
Having said that, I find that erotic art (drawings) generally more arousing than most pictures. I grew up drooling over Vargas girls, and then Bishop began airbrushing. Some of my other favorites are DeHaro, Paul, Damien, and many others. My all time favorite, and Mobius will agree with me, is Gary Roberts. Many of his works show two subs in the picture, one being tortured, the other watching in anticipation.
Whatever the medium, I prefer bondage as at least some part of the scene.