This poll is likely going to be skewed by what people currently have or are familiar with. And, let's face it, most of us do not and likely will never have a Steyr AUG or any SCAR variant.
Something in .308 sounds good, but, humping around enough ammo to feed it will be NO FUN.
I think your going to see a LOT of AK and AR votes on this poll.
Me? I went with the AK because I have much more experience with it than I ever had with M-16 variants while in the USMC. Meaning, I have a helluva lot more trigger time on my AK than my M-16A1.
Additionally, I prefer throwing .30 caliber lead. The AK has simpler inner workings and the round is good enough to take care of business at 300 yards and less. Any further than that is likely not going to happen and if it does, then it's time to call in the fast movers or artillery.