Like Graycg I have barrels from SSK, Bullberry,T/C factory, Van Horn, V.V.C.G. and MBMCO(OTT), the following is my experience and as is usually stated your mileage may vary:
SSK--Very good quality, a bit pricey
Bullberry--Very good quality, a bit more affordable
T/C Factory--Usually pretty good
T/C Custom Shop--Can't tell any difference from regular factory barrels.
Van Horn--Very Good quality, superb accuracy. Several barrels
V.V.C.G.--Very Good quality
OTT--Very Good quality, superb accuracy. Several barrels.
The order in which I would purchase a barrel from these followes,
OTT
Van Horn
Bullberry
V.V.C.G.
SSK
T/C Custom Shop(Fox Ridge)
T/C Factory
Bear in mind that barrels are made by people and everybody makes a bad barrel every once in a while, some more than others.