There are many good barrel makers that do a good job on pre-fit barrels. You typically get what you pay for and top tier barrels are the same. Some people swear that their favorite brand is the best, but many records have been set by many different barrel manufacturers.
I would personally be a bit hesitant on E.R. Shaw. Some love them but I haven't seen much from them that makes me feel like its an improvement over stock. I'd rather find a factory take off for a fraction of the cost. Now, if its a chambering you can't get from the factory in the contour/length you want, it's a tougher call. Douglas, Pac-nor, Mcgowen, Shilen, Benxhmark, Lilja, etc, are all top tier manufacturers with prices that show it. The barrel market is pretty competitive. Keeping in the same price range typically results in similar quality levels.