If you buy more identical pairs of socks, if some of them get destroyed, you can make pairs of the remaining ones. On the other hand, if you buy similar pairs, you will waste a lot of time sorting them.

I recently had a sock cull, in which I got rid of every sock that couldn't immediately be visually matched with one of its fellows. I must've reduced the total number of socks I have by about two thirds, but the overall availability of matched socks is now much higher.