M1A all the way, I've shot M16A2/A4s, M4s, AR15s, and some AKs and for me the only thing thats more fun to shoot than my M1A Scout is a belt fed weapon which are hard to come by for $1500 (ok more like impossible).
Best investment I've ever made in a firearm hands down.
Sgt. of Marines, 5th Award Expert Rifle, 237/250
1st Award Expert Pistol, 382/400
D Co, 4th CEB, Engineers UP!! OEF 21JUN-20SEP2011