I had a Frontiersman and foolishly sold it. Solid, rugged blade. I would be more than happy with it in any scenario.
I've never used or held the Schrade, but it's a stout looking knife as well.
To be perfectly honest, I wouldn't use either of them at this time. They are no longer made and both seem to command a premium on the "collectible" market for fans of both companies.
Forced to pick, it would be the Buck, because I've owned one and know what it can do. I also like Buck's stainless steel more than I do Schrade's. I was never really pleased with a stainless Schrade knife. I always bought the carbon steel myself.