Don't take anyone's advice.
Read the $28 book that spends hundreds of pages with useful data and analysis on precisely this very question.
http://javelinpress.com/bostons_gun_bible.html
If you don't think the book is worthwhile, I'll buy your copy.
Trust me.
(It likes the M1A, but explains why, and explains why you might like others.)
I've read it, why is one reason I'm leaning towards the M1A right now.
I just got done with "Molon Labe", which is the latest from Boston, and I thought it was great. Have you read it?