As far as I know, there's not really any accuracy difference; they're all really good, and they all had to meet the same accuracy specifications (something like 5 cm at 150 meters, if I recall correctly). Best group I've gotten from my VKT M39 so far is 1-3/8" at 100 yards, using Wolf 148-gr FMJ.
I think the Sk.Y's are the most expensive, but it's not because of accuracy, it's because they (1) are rather rare and (2) were issued to the Finnish Civil Guard, which I think was something of a civilian militia or national-guard-type organization rather than an actual military branch.