In the Army the popular folders are the Buck Strider, Gerbers (cause they are sold through the PX), and Benchmades.
The fixed blades are Benchmades, Cold Steel, and SOG (especially the Seal Pup). You'll still find the USMC fighting knife (kabar) and pilot survival knife (my kit knife for years).
Any knife with an NSN is going to be more popular than one without. A lot of my soldiers carry the ApplegateFairbain folder because they get them as a re-enlistment bonus. Ontario RAT-7's have an NSN but I haven't seen anyone carry them. I've seen a couple BM Nimravus around.
The sad truth is that there just aren't enough Busse kin knives in existence to be a significant portion of the carry blades for the armed forces. The Army alone is over a million strong (including our Reserve and NG members).
I just bought my first Scrapyard knife, a YardGuard from ebay. It's a heckuva blade, now it just needs a MOLLE compatible sheath.
