I'm just going to toss one more name into the pot... Steyr.
The MA1 series is an excellent choice for military or police. As good or better than the M&P (my EDC). The "Trap" sights are tailor made for a combat sidearm. Quick aquisition and pinpoint accuracy in one package. If the M&P had these sights available it might take over 1st place in my mind. However, there do seem to be some reliability issues with the M&Ps. I haven't had any problems with mine but have seen/heard enough to think there are some real kinks for S&W to work out.
The argument of which caliber will never end.
I want .45 if I have use ball ammo. 10mm is my next choice followed by .40 and lastly 9mm. If things change and JHP is allowed then go with 9mm as the most widely available ammo out there. I know the Steyrs are not available in .45 or 10mm. this is just a personal pref in caliber.
I won't comment on whether I think the US military will ever adopt Poly or Striker fired weapons. I didn't think we would ever issue anything but 1911s until I found myself in Iraq with a Beretta!