The SIG M400 is my choice... there are too many good things about it. And that's why I have it over the others mentioned in this thread. It is very well finished etc and shoots MOA shockingly easily. Good use of chrome throughout the gun and it is immaculate.
The progressive 5R twist on the M&P comes close second for me. The Bushmasters I handled did not feel right. The SIG really is aimed at Military and Law Enforcement. That speaks volumes.