I can't narrow it down to any one knife (or person) in particular, so here goes:
Sebenza - what can I say - "quintessential". Chris and Anne are setting the standard for customer service and consistency of quality.
Bob Terzuola ATCF - introduced the thumb disk, first "tactical" folder, cool logo. Bob can design a freakin' knife!
Spyderco Military-second edition - shows that persistence pays off, eccentric pivot, design, tough as hell. Danelle, where are you?
Cold Steel SRK - for the money, a terrific all-around FB, in spite of the company's politics.
Simonich Cetan - design, TALONITE. Rob is too cool for words.
Kit Carson Model 4 - one of the few customs with liner-locks that can be implicitly trusted, overall design, built like a brick doo-doo house, and above all, Kit is a another "classic" of sorts.
Benchmade Emerson CQC7 - Navy Seals, and Richard Marcinko were catalysts for the lightweight tactical folder revolution, at least for me. Yes I bought in to that "issued to Navy SEAL's" crap. Admit it, so did you.
Spyderco Police, Endura, Delica - Wunderbar lockbacks. Sal Glesser, the man behind the one hand folder revolution. The Tucker (without the crappy outcome) of the last 50 years. Why can't corporate America be more like Spyderco?
Too many more to list - enough of this novella.
Later,
Chris