There's a website that lists FPS registered Friesian stallions with reviews on them. (To be honest I'm just browsing around to look at my buddy Apollo
Apollo's not an FPS approved stallion he was invited to be approved though, as for his offspring, I've only met Conquer, and he was pretty fantastic by my standards (Though i'm new to the horse deal) He was sweet, active and cute as a button (Now you know my standards lol). FPS approved stallions available in the USA
Has a list, that's pretty long. Friesain Exchange
Is a search for good stallions, may help you find what you're looking for.