Initially, none. You won't be able to have much in the way of knives for at least 3-6 months after enlisting depending on your MOS. Scratch that, you won't be able to have ANY knives at all for the first 2 months, they even take scissors and nail files from you at Basic. I've been in the Army now for almost a year, and in my experience so far, you'll get the most mileage out of a Leatherman or Swisstool and a nice tactical folder with a 3" blade or so. I specify the blade length because some units have a length limit. I'm in Korea right now, and I can't have anything over 4", fixed or folding. In garrison, I carry my Swisstool and a Camillus EDC with a 154CM blade. When we're in the field, I add a REKAT Fang to my LBV. On our last field exercise, that combo served pretty well for everything I ran across.
I realize that I'm not really answering your question, but I wanted to point out that the traditional combat style knife with a 7" or larger blade is against the regs at quite a few installations. It's disapointing and frustrating, BELIEVE me, I know, but it is the reality. Also, keep in mind that if you're a single soldier living in a barracks, chances are very good that you won't be able to keep anything big, like a Ka-Bar or your Chris Reeve, in your room even if it is allowed on the installation. You'll probably have to store it in the arms room. They'll issue you an M16 with live ammo on the range, but you can't have a Ka-Bar in your room. Makes no sense to me either.
In response to your original question though, I'd say a Busse would be an excellent choice. I don't own one, but I've heard many, many good things about them. I'd probably get the Steel Heart myself, since a 7" blade is the most practical size for a combat knife in my opinion. The Becker C/U 7 looks really nice too. I would have one now if I were allowed to have it here, but circumstances don't permit it right now. Anyway, good luck with the military, hopefully you'll go to a nice unit where you can have all of your fun sharp objects. Just remember to read the fine print when you sign your papers!