I wear a 9.5 womens shoe and I buy the large Solmate socks.  I love them because they are cotton, breathable, warm, thick and I like the styles.  They do shrink a bit and the size medium was too small after washing/drying.  Durable.  Nice construction.

I like these especially because I can wear my water sandals into the cool months with these socks.  I do not wear them with regular shoes, they are thick.  I also wear them around the house in place of slippers.

Update: I have worn many pairs of these for nearly a year and I still love them.  I do wear them with tennis shoes and wore them with winter boots.  Still wear them around the house. These are so comfortable that they make regular socks feel like nylons.

Do others like these as much as I do?