Above are two images of the Hawken rifle I built while I was working for Don Robinson here in Prince George during the early 80's. Don reserved the first ten serial numbers for prototype and personal rifles, and this one is # 5. Originally, I used a .50 calibre GRRW barrel, and built the rifle, only to find that I could not make it shoot. I re-barreled it with a Green Mt. .54 cal barrel, and it was a wonderful shooter. At one rendezvous, we had an 18" gong hanging at 200 yards, and I was the only one to hit it every time - offhand. So I invited anyone else who wanted to use my rifle to try, and six shooters in a row hit the gong with their first try.
Back to the discarded barrel...another builder bought the barrel from Don and built his Hawken around it. But he RE-CROWNED the muzzle, and the barrel performed very well after that. So, it was not a $#@* barrel, but a poor crown that was causing the trouble.
The point of all this, is to show that just because a shooter can't get a rifle to group does not necessarily mean that he has a poor barrel. I return to Don Getz comment that if the barrel is uniform in the bore over it's whole length - no loose or tight spots, and is rifled, it will shoot better you can hold it. So my first test when buying a new barrel is to run a very tight patch on a jag down the bore. If it is uniform in the bore, I have more confidence that it will be a good accurate barrel.
I prefer barrels that have narrow lands and wide grooves, rifling ~ .012" and square rather than round bottomed. Yet my wonderful little Jaeger has a 31" Getz .60 cal. barrel with deep round grooves...go figure. i don't think there's any one answer to the question.