Without doubt, Thompson Center. They are/were the most solidly built and most widely available ML for years. CVA's were close behind, in terms of availability but IMO nowhere near as durable as TC. I own both and the difference is easy to see. Actually, the Lyman GPR I have is more solid than the CVA. With that said, the CVA's can be very good shooters and do not have the less than desirable shallow grooves as the TC's have.