There is no one name answer to your question. There are 60+ gunmakers who can make you a "best" gun by anyone's standards. Generally, they work as a world trade these days; barrels, actioning, stocking, engraving, finishing, etc. all done in different countries. Such guns are usually +$50,000 and many months in the making. Some of the very best craftsmen are literally booked for life. There enough people "voting" for their favorite craftsman at $50,000 - $100,000+ a pop to keep all these 60+ guys in business; as I said, no single answer.

Were I "voting," I'd "vote" at Hartmann & Weiss.