Two of my all time favorite sock yarns! Knitting them both at the same time has given me a really good idea of the differences and similarities between these two yarns. First the similarities: both of these yarns could be called "heavy" fingering or maybe "very light" DK yarn. The thickness of both the Wildfoote (by Brown Sheep Yarn Co.) and Paton's Kroy are very close to the same.
The Wildfoote is "rougher" in the hand - it feels more "scratchy" than the Paton's Kroy, which is quite soft. Once they are washed, however, the Wildfoote is very soft, too. I also find the Wildfoote to be ever so slightly more "splitty" than the Kroy. Not enough to cause trouble and certainly not a deal breaker but it is something I noticed.
Wildfoote is one of the first sock yarns I used and I still love those socks - very soft and cozy. Once the socks with Kroy are complete I think they will feel much the same. Two very good sock yarns!
Wildfoote is mostly available online although there are LYS around that carry them. I just bought some at my local shop in New Orleans (which has since gone out of business, sadly) and I also bought some at a small yarn shop in Portland, Oregon last summer. (Starlight Yarn Shop) The price for Wildfoote is around $8.00 - $9.00 per skein (you'll need 2 to make a pair of socks) and comes in lots of nice colors, solids and variegated. Kroy is sold at Michael's as well as Hobby Lobby here in the States and the cost is about $7.00 per 50 gram skein - you'll need 2 skeins to make a pair of socks. Nice variety of colors.