It's really hard to beat any manufacturer listed , especially Larue. The OBR is typically sub MOA all day. Personally I have an LMT due to its availability (no year wait like Larue and other custom gas guns), durability, reliability and accuracy. The British selected it as their DMR rifles, our spec ops have used it on a limited basis some too, and although heavy it will run with the custom guns for most shooters. As with all military firearms, it has survived numerous hard use and torture tests meaning it will nearly always be running without issue.
After a five round sight in, I was able to shoot consistent 3 shot groups at or under .5" with 168 gr Federal GMM (Bushnell DMR 3.5-21x with G2 reticle). No it's not five shots and yes it was only 100 yards, but I believe it demonstrates the accuracy potential and puts LMT up there for the money with Larue, JP, etc. This was done off a bipod as I don't have a bench rest at the moment. Can other guns shoot more accurately? Maybe, but can I? Probably not. When you can cover the rounds with a dime, I can't ask for much more. Iive always shot 3 shot groups and personally wouldn't consider 5 necessary when evaluating a gas blaster. Your real challenge with gas gun accuracy is going to be the loss of velocity from a short barrel for extended range shots anyway. A gun that is sub .5 moa accurate is going to do its part to 800 yds (1,200 if you are Todd Hodnett and the boys at Accuracy 1st).
Additionally, some have mentioned the 6.5 mm ballistics being superior to the .308, and I agree. But with the purchase of extra barrels and two turns of a torque wrench I can be sending 6.5 Creedmore or .260 Remington rounds down range from the exact same MWS platform. With ammo availability fluctuations and different hunting scenarios, the LMT is the best option to shoot different calibers depending on differing situations with the same gun. There may be more accurate custom guns out there, but for the overall package I don't see how you could do better than an LMT MWS, unless weight is more important than repeatable accuracy.