My husband's big sexual turn on involves masturbation.
I have seen where it seems most men are turned on most (aside from pussy) by a woman's breast. I know most of my old boyfriends and my ex husband sure were. They loved to kiss and fondle them and suck on my nipples gently biting them. But, my man now is turned on the most by my legs mainly the feel of my inner thighs. I first noted this when we were going out together before we married when our relationship got intimate. When making out as couples do the first place his hands went was up my skirt. Not under my blouse as I was used to. He often prefers doing this to actual sex (intercourse). He has also brought me to orgasm and then will pull out and have me perform this on him to get him off.
This involves my laying on my left side with my left leg out on its side. My right leg will be propped up. I then take my right hand and lube it up real good and he'll take his erect cock, lay it on my left leg's inner thigh and have me rub it against the soft flesh there. The feel of this area against his cock drives him nuts. All the while his left hand is roaming over this area on both my legs. He especially loves that area women have there just below the crouch. He has told me that this is the softest place on a woman's body. It doesn't take long and and he'll start really getting into it thrusting his hips some stiffing up and shaking a little and with a loud grown he'll start squirting his cum all over my leg. Sometimes I even end up with a rope or two of it in my pubic hair. I think he enjoys this as much as he does being in my pussy. I'm just glad that I have these nice soft shapely legs that turn him on like they do and brings him so much sexual pleasure.