Polyester and its relatives
appear to provide the longest life.
I suggest that you look for polyester to be the first, or largest
percentage of the sock. You may pay a bit more, for these socks
but your feet will be happier. A soccer players feet are the
most
important, aren't they? So why not invest a little bit more for a good
pair of socks.
Colors
They are available in an endless number of colors. You can support
your favorite club side with a pair of their socks while in practice,
but you must have your team socks for a game. After all you are part of
a team.