Hi bflem55. I don't have an AR but certainly fired an M-16 regularly back in my military days. About a year and a half ago I opted to get a Bushmaster M-17S Bullpup rather than an AR. I have to tell you that the M-17 is definitely more comfortable and better balanced than the AR's. They accept AR/M16 mags and fire .223 ammo, has an ambidextrous magazine release, a 21.5 inch Match barrel. They have fixed "25 meter" combat sites but are also set up for optics with a "see thru" Weaver type rail attached.
If you're not familiar with the bullpup design, the action is set behind the trigger which allows the overall length of the firearm to be shorter and more compact without cutting back on your barrel. The trigger being set further ahead makes your hold on the firearm much more natural and overall much more comfortable to shoot.
If you're interested you can take a look at one on the Bushmaster web site ( www.bushmaster.com ) and it just do happens that there is one listed in the classified ads here at hunting.net.