The older M1A you can find, the better.
When the government canned the M1's they cut up all the recievers and let the salvagers buy up all the parts. M1's were built back when the army had to budget to get the best money could buy. It is cost prohibitive to reproduce some of the parts the way they were originally made. The operating rods were hot forged. Barrels were chrome lined and them tested. Out of spec barrels were discarded.
The older civilian M1A's were built using the best pick of the original GI parts. As GI part supplies have run out builders have had to start using non milspec parts. The best guns where made in Devine Texas back before the current Springfield Armory bought them out. These preban guns shoot great and were hand assembled using all GI parts on a semi-auto reciver. Scott Duff has a great book on the M1A that will tell you how to spot non GI parts. You definitley want a gun with the origianl GI operating rod. It is a critical part that gets a lot of abuse. Go for an original preban gun if you can find one. I hear good things about Fulton Armory rifles but have ever fired one. I have a post ban Springfield with a NM barrel (Springfield for not and original military or chrome lined bore) that shoots great. Op rod is GI along with the trigger and hammer. I didn't like the oversized NM stock and put an original GI one on it. I got lucky and it was all GI parts but the barrel and stock.
I hear lots of stories about the later Springfields not holding up if they are shot a lot. Operating rods bending or braking are the biggest complaint. Sometimes after only a few rounds. You can still find operating rods new in the wrapper for on several of the auction sites but expect to shell out $250-350 on one though.
That all being said, the M1A is a fun and accurate rifle to shoot. I like it better than my AR-10 and on par with my SAR-8 (Hk-91).
I've had some neat semi auto 308 rifles but my recent Springfield M1a standard model is my favorite. I love the wood stock, handling, and it's easy to shoot.
I've update the spring guide/operating rod and gas piston with Sadlak units. The gas cylinder has been replaced with the springfield welded unit. She shoots better than me and I'm always happy when I get to the range with her.
They are surprisingly accurate and yes, I would not sell mine. Literally, my Supermatch will be one if not the last gun I ever part with.
Here is my Super at 100 yards, 50 shots off the bench.
This is the National at 100 yrds, 50 shots off the bench.
They are good guns, accurate, reliable, fun to shoot, easy to reload for and very distinctive. I doubt you will not love one. At one time I had around 6 or 8 but paired back to these two as my safe got full.
I used to collect M1A's. While it is really hard to make a good comparison, the loadeds are likely "more reliable" because they are slightly looser then the match guns. You can feel it when you handle one.
I don't remember many jams with my match guns after I got my reloads tweaked, so it is hard to say which is really more reliable.
I found the match guns go about an 1 to 2" better at 100 yrds then the loadeds on a 50 shot group.