I would go with a custom smith if I were going to buy a serious knife. It might cost a little (or a lot!) more but you'll get exactly what you're looking for.
If you're really into a khukuri try these guys:
http://www.himalayan-imports.com/
or these guys:
http://www.thekhukurihouse.com/
(I think they were once associated with each other and went their separate ways.)
As for "tactical" or "survival" knives, Swamp Rat has been known to make some pretty tough stuff.
Buy a few copies of
Blade and look around for what pleases you most...