Both rifles will probably be as accurate as you ever need them to be. The AR-10 won't be necessarily easier to keep in match trim, if that is what you are after, but it will probably be cheaper. With the M1A, you can either have your rifle bedded, and re-bed it as necessary, you can save yourself the hassle and spring for one of the chassis systems on the market (Troy, JAE, Sage, ect) that eliminate the need for bedding, or you can accept the rifle is probably already more accurate than you are and is likely to remain so for the foreseeable future.
Some chassis systems, notably the Troy Ind., also make it easier to mount a scope. Most have plenty of rail-estate for you to mount gizmos and gadgets from.
The AR is easier to field strip, but not necessarily easier to clean. With the AR, you inevitably end up with a bunch of crud in the receiver, lots of small edges and corners, and that #!*& star chamber. The M1A really requires only a 3/8 socket wrench (or purpose built tool) and a quick wipe down of the gas system every couple hundred rounds. The receiver, bolt, and chamber stays clean and cool enough that it only really has to be cleaned once in a great while. I cleaned mine every 200 rounds or so, but there was so little to clean at that point that it really isn't necessary unless you're in a habit of dropping your rifle in the sand.
I personally prefer the M1A, giving it a slight advantage in ergonomics, balance, and control placement. Most or all of these are admittedly personal preference, as is my huge preference for the overall feel and shooting characteristics of the M1A. While the M1A comes across as a serious tool, a rifle built by and for riflemen, the AR always looked, felt, and operated like a toy to me. Even being trained in its use, I knew I could keep it running, but it never inspired my confidence. The sound of the buffer spring in particular always made the rifle sound like a cartoon to me, and I was never able to get over it.
Like the above poster, if I had the money, I could easily see me with a large collection of M1As, FALs, HK roller lock clones, and AKs, but perfectly content without every owning one of Eugene Stoner's Wonder-Rifles.