16" is about the standard anything less than 16" total will make it a short barreled rifle and you will have to jump thru all the hoops for the $200 tax stamp and the 6 month wait . What is your intended use ?
Go with either 14.5" with a pinned muzzle device or a 16". If you go 14.5", give the muzzle device serious thought because once it is pinned, it will cost you much more to change your mind. I am an Authorized Noveske Dealer, so if you aren't set on a particular place to get the barrel or upper from, feel free to contact me and I will help you out. I do not have any Noveske barrels in stock, but I can order them. PM me for a very competitive price quote.