Women's armpit can be very erotic too whether with hair or without hair..
Also erotic is the flesh around the armpit especially the web of flesh joining the arm to the breast.
Many men don't like women have hair in their armpits. I got interested in women's armpit hair after one incident. On one working assignment, the team I was working with had an attractive woman. Of course I looked at her more often.
On one instance she raised her hand and I found that I could see under her sleeve. I saw enticing black hair. The view lasted just a a second or two. I found it very erotic.
From then on I became interested in women's armpits whether got hair or no hair. The best are those with some fine hair.
a nice armpit
another nice one, imagine some fine black hair on it...more arousing
The dark creases make the pit more sexy
The smell of the armpit is a great stimulus to many men.