Short nails are attractive even with a little dirt under them. I don't like excessively long though and some fake long nails are not attractive. I do like well groomed all natural long nails all the time and I love the feeling of nails being dug into me/scraping across my back/arms/whatever you choose while I'm penetrating her. Every now and then if she does it in the right places I do like the feel of nails being dragged across my skin.
Surprise me. Each one has its own attractiveness. The only preference I have are with red heads. I love seeing that red ;)
I know I shouldn't masturbate in public where I can get caught but it turns me on too much not to