Both.
Your first post, was that BOGO offer?I mean, an 11.5 makes sense for CQB work, its what I setup for me when I was in LE. However a 16" 5.56 gun can work at extended ranges. I think the question that has more weight is what working environment do you expect to deploy the firearm in. If it is only one to stretch out amongst multiple roles I would lean more to 12.5/13.7/14.5. Also if you travel alot a braced pistol has some merit over an sbr as well. Also what optics are you thinking about running. We could probably discuss this topic for days on end lol.