Bang for the buck:
Spyderco/Byrd - great quality, wide range of prices and materials offered, innovative, great customer service...something for everyone's price range. Love the Byrd line, can't believe what you get for $30.
Benchmade - top quality and fit/finish that rivals customs, great designs, axis lock and great liner and frame locks too, wide range of prices.
Buck - quality build, great warranty, very affordable if you aren't looking for the next "Steel of the month" exotic materials and catchy marketing.
Kabar - beat them to death and they still perform with minimal maintenance.
Kershaw - nice designs, love the assisted openers, very affordable, great customer service.