Criterion AR10 Barrels
Criterion make premium barrels and they were formerly a part of the world famous Krieger Barrel company until they were sold by John Kreiger to one of his most experienced barrel makers. Criterion Barrels are button rifled hand polished and correctly heat treated. If you want an accurate AR10 this is the first place to start.
My personal experience with AR10 rifles has shown that the barrels on many factory guns are average and a simple barrel swap can get you that SUB MOA accuracy you want.
If you are wanting to suppress the rifle I would recommend the 18" barrels not just for overall length but the 18" barrel will not overgas as much as a 20".