There is no single manufacturer that is acknowledged as producing the best barrels. You'll find among the target crowd, Krieger, Hart and Lilja get mentioned more then others.
In this day and age, more accuracy is gained or lost by who cuts the chamber, and fitst the barrel to the action, then who made the barrel. Not that money gurantee's quality, but I'd venture to say that a $200 barrel and a $400 fitting by a smith will outshoot a $400 barrel fit for $200.