Shirogorov
Chris Reeve
Benchmade
Spyderco
Zero Tolerance
Those are more or less in order. I do prefer my Benchmades to my Spydies, but have many more Spydies than ZTs. It's hard to say I like the former more than the latter--they're just so different. As to the top three, price-point plays a role, as I feel I damn well should like a $1000 knife better than one at $500, in turn better than a $250 piece. That's not entirely the case, though, as each brand has it's place in my carry, use, and affection.