I was going to select FMJ until I saw the part about ignoring the Hague conventions. Then I opted for JHPs.
Why JHPs? Tough choice, and I was still tempted to choose FMJs due to the advent of bullet resistant body armor. I'm also figuring that since cost wasn't listed as a criteria, that it isn't going to be figured in -- and there is a pretty big difference in ammo costs between FMJs and JHPs. I still figure that there's no real reason to choose JSPs, as they won't really expand enough quickly enough to be any real advantage.
First, combat body armor -- of the military variety -- is going to stop FMJs as well. Second, modern design JHPs are pretty good at barrier penetration, so that isn't all that much of an advantage in the FMJ camp. But mostly, I am looking at the mission of the handgun in the combat military role: Close in, last ditch defense against heavily armed opponents. Meaning, real "knockdown power" is needed, quick incapacitation is the order of the day. Yes, I know that no handgun really gives you anything resembling knockdown power, but quick incapacitation is vital, and the quicker the better. Sounds to me like JHPs would be better in that role than FMJs. Of course, this is all academic -- we are committed to the Hague accords, so FMJs it is.
Even so -- I feel that a good case can be made that the current operations that we are undergoing in the ME are not covered by the Hague accords, which only apply to conflicts between uniformed armies that have definite command structures. Since the adversaries we face are not uniformed and have no clearly defined command structures, technically we are not bound by the Hague conventions in dealing with them -- they are terrorist criminals and can be treated as such. They have no protections at all under the rules of war. As such, I feel that we would be justified if we were to "take off the gloves" when dealing with them -- ditch the FMJs, and forget about those rules that don't apply to criminals.
OTOH, there are still some Bathist/Taliban military cadre that are operating with the terrorists, and their status is questionable. With that in mind, one could make the case that since a few of the opponents might be covered by the rules of warefare, we are better off being conservative and sticking with the more conventional armaments.