I'm a huge fan of Trekking XXL. It's really tough stuff, comes in pretty colors and it's resilient to wear without being too rough. You can get a pair with some left overs with one skein, around $17.
Also, any of the Panda's will do: Panda Silk (criminally soft stuff, but slick), Panda Wool and Panda Soy. These aren't cheap, though, and you need at least two to get a pair, but more than likely, four. They can run about $9-10 a skein.