I wasn't aware that there were too many specifically advertised fox hunting sires although I guess the ISH and RIDs are the closest. Most of what I see in the hunt field is OTTBs, Draft crosses, QH crosses and Paints with a sprinkling of warmbloods. What you breed depends on what you personally like but I think most fox hunters were bred for another use or for multi-purpose use like eventing or show hunters.
My two favorites are Box Car out of Oklahoma and Tractor Trailer out of Canada
Add Wyoming to the geography!
Seriously, I agree w/gypsymare, Ireland seems to breed more for the 'hunting type.' There just isn't enough of a market in the US for a breeder to stand a sire particularly for foxhunters. I've know OTTBs, TB crosses, quarter horses and many others with many good sires in their backgrounds. You can look to the lines that produce good jumpers like Bonne Nuit- but that is just one of many variables that go into a good hunting horse.