The M1a is my favorite, Excellent sight picture and excellent adjustments that do not need tools, even bullets to make those adjustments. Trigger is completely usable. ( I had an m25 whitefeather with the Rader trigger at 1.5lbs, wow!!! but no more) Excellent accuracy, excellent reliability. Built as an improvement on the M1 I think it accomplished it's task. Excellent stock design, it points like a good shotgun with the standard military stock, gentle recoil, I've shot mine in a tee shirt many times.
Positive features.
1) Excellent sights, repeatable, hand adjustable for windage and elevation past 1,000 meters.
2) 20 round capable as issued.
3) stripper clip feedable as it comes from the factory.
4) Reliable with military ammo, in the jungle, desert or arctic environment.
5) points very well.
6) with a 200 yard zero, no practicle holdover is required up close.
7) accurate to 600 meters as issued with military ammo. 2 minutes of angle or better.

low recoil.
9) 2 stage trigger is repeatable and dependable, pretty darn good as it comes from the factory.
10) meant to be used with a sling, carried and fired, with no shift of zero.
11) bayonet and butt stroke capable.
12) as any good military rifle, you can break it down into it's components for detailed cleaning without tools.
13) elegant is not a mechanical feature but I think they look that way.
Negatives.
1) It's heavy.
2) unless you pay big bucks, optictal mounting is iffy at best ( I'll address this again later ).
3) a little long for my taste in close encounters, but shorter ones are available.
Now I have an m1a scout config. l liked it the way it came with an aimpoint comp m2 and fiberglass stock, but I purchase the Troy industries modular chassi, to convert it to an AR type platform with full length 1913 rail on top, and rails at 3, 6 and 9 o'clock. The stock is technically lighter, but it changes the balance dramatically, I have not shot it yet and will with hold comment until I do so. Scope or any optic mounting problems are solved, and the magwell is bigger. I've got a collapsible car15 stock on it now, but if it performs well, will go with and ace SOPMOD 4 OR 5 STOCK. Looks cool, but race paint don't make a race car.
There are many M1a's, BUT THIS ONES MINE, HER NAME IS MYRNA.!!!!!!!!!!!!!!!! after my mother.
Like my Mother, she has NEVER let me down, For any of you who shoot US service rifle, I got my first leg points with this rifle, I shot a 464 out of 500 with issue match ammo and no sighter shots. The course of fire was out to 600 yards. At the 200 yard standing course, I can't remember my total score, but out of 20 shots, the last 12 were 10's and x's. With this rifle I truly believe, If I can see it, I can hit it.!!!
Sorry for the long post, Elvis has left the building.