I am in the market for a new AR. I had one a while back and decided I had to have something else and I couldn't have been more wrong. I had an RRA in .223 20" and really liked it. I recently shot a friends DPMS 16" carbine setup and realized I had to have another AR15. I am thinking I really want a 16" carbine or midlength free floated barrel with a railed system. I can't decide now whether or not I want a .223 or 6.8? I have prior knowledge of the .223/5.56 platform but I have always been interested in the 6.8SPC. Opinions please.