I would say carry a multi-tool first, whether it be a Leatherman, Vic or Wenger SAK, or SOG.
Then, take whatever fixed blade makes you smile. Most of the time (and I hope most would agree with me here), we spend our time admiring our knives....sharpening them in search of the scariest, most frightening, most blood-curdling horrifically sharp edge.... showing others how easily they cut this or that.... and sheathing and unsheathing the beasts. Then we go camping, hiking, or hunting, and use them for several minutes before it's back to admiring them. (Am I the only fool here who does this

)
So, in my opinion, consider weight, policy and regulations, etc.... then get the knife that makes you the horniest.
EDIT: Ah yes, Bulbboy, what a reminder. Keep yourself safe and come back alive and ready to buy more knives. And remember, despite the all news coverage that the whiners and haters get, there are many millions who cherish and appreciate what our soldiers do...here and abroad.