Go with the AA, I've played with both and find the AA easier to clean and more accurate (yeah yeah I know.... shouldn't have any impact, paint to barrel fit blah blah, but I'm only saying what I personally have found)
It was also pointed out to me that playing front/mid doesn't mean you should be opting for a shorter front. I use an 16" front, which helps push the pieces in when shooting, allowing me to stay slightly tighter.