Buck.
Everything from slip joints, classic lock backs, modern folders, hunting knives, large fixed blades, etc...
I really like the wide range of their offerings, and feel like i could fill all of my niches from this.
Next on the list would be Cold Steel. They have, as far as I can tell, the widest breadth of product line with everything from small folders up to machete and such. But I prefer Buck's products on a whole and could do just fine forever with only Buck's product line. In fact, even discounting their Chinese stuff, I could do just fine with only Bucks american made product line.