I started out with collecting all of the Uncle Henry and Old Timers, but that soon gave way to collecting older Schades and related manufacturers. Still always on the lookout for a "good deal". Most of my knives are Schrade, but I have a fair number of Ulster, Craftsman, and Camillus too. I really like Western Cutlery from Boulder Colorado too, but they are tough to find often. I also have a dozen or so Case knives, mostly recently made ones.
My collection now consists of mostly folders, and I really like the Schrade Waldens, picking up bone handled versions when available. I pretty much concentrate on knives in excellent condition for their age. I also like finding nice used ones to carry and use. I don't discriminate on pattern or size, and collect them all. I would love to collect the Schrade Cut Co era, but it is difficult to fine them in the condition I prefer.
For the most part, while I have my favorites from time to time, that changed with the wind. Any of my knives are for sale for the right price at the right time. No exceptions.