Glenn, the most accurate flintlock, would be a very expensive thing with a custom false muzzle barrel and sights that cost in the hundreds of dollars. Definitely not a hunting gun.
If you mean a reasonably priced production gun available at a gun shop in a box, I'd say Lyman Greeat Plains rifle is probably the best production flint gun out there.
If you could find an old flintlock CVA Mountain rifle, it will have a more accurate shooting barrel than any current production gun.
TC is a good overall gun, but they have some problems with their flintlocks.
An Italian InvestArms Hawken style gun, as sold by many mail order outfits, is a close second to the Lyman.
A hunting gun serves a different purpose and really isn't capable of the fine accuracy for international Muzzleloading competition.
Bunky, Loggy and Mccoy are so very right about a custom gun with a premium barrel, perfectly engineered lock and a stock made to fit an individual instead of a production gun made for a range of statisticly average persons. A custom gun can be made to fit you in cast off, drop and pull. A production line is more interested in using the planks they get the best deal on, rather than best fit.