Mike Rock and his Rock Creek Barrels have an excellent reputation. Very fine cut-rifle barrels. Several of my friends have them on their rifles.
Most of my custom barrels have been from Krieger, although I too have a Hart that shoots great. http://www.kriegerbarrels.com
Most of the custom barrel makers offer a very good product. It's fun comparing all the different barrel makers, but I'd have a long talk with the guy building/re-barreling your rifle, and seriously consider his recommendation. Many smiths have a particular barrel builder they like working with.
Broughton also has an excellent reputation these days.
Custom barrels are a hoot - I think you're going to like the results you get from any of the good barrel makers!