It may depend on what's available in your area and more importantly what your smith recommends. (I assume your barrel is not yet threaded for a brake.)
If it was me here in the US and not shooting prone, I'd lean towards Vais or KDF.
If shooting prone, then I like Darrel Holland's. The CSR Muscle Brake is also very effective, but my personal preference for looks leans towards Holland's radial brake as a Blaser is a fairly stylish rifle.
