If i was buying new cable for controllers, i'd be picking UTP Stranded Cat5e. "U" = unshielded Twisted Pair.. While Cat6 is capable of higher bandwidths, we are talking 10GB vs 1GB. Cat5e is more than adequate for controllers, most of which are just 10 or 100M. However since your likely to be connecting your PC as well, at 1GB then its a good choice.
Cat5 is probably almost unavailable these days, and if you can get it, its probably more expensive than cat5, just because of the amount of cat5e thats used. Cat5e is a lot more flexible than Cat6 as well, because it deostn have an internal former in it.
Essentially the difference between Cat5, Cat5e and Cat 6 is pretty simple. The specification of the twist in Cat5e is tighter than Cat5 and cat6 has an internal former in it, so it keeps the pairs in position to each other, which keeps crosstalk lower..
If you have an environment that is so noisy that you really need STP ( Sheild Twisted Pairs ) then you might actually be better to look to relocate the noise source or the controller away from it.