Of the ones on your list, I'd get the ACR, because I think it's cool and versatile and just so I could get everyone to ooooh and aaaaah over it at the carbine shoots. Of the one's not on your list, I'd get a Colt 6920 (because I like mine a lot) or a BCM of any configuration because they are both full mil-spec rifles and MPI bolts and barrels, and proper staking matter to me.