RE: Flintlock???
PaJack.. that depends on how much you are will ing to spend, the caliber you want, and the type of projectile you want to shoot.
Some of the more common production rifles of good quality are the Thompson Center Hawkins, Renegade, or Firestorm. Lyman makes a number of good flintlock rifles like the Great Plains, The Trade Rifle, and the Deerstalker. Traditions also makes some good rifles. They have the PA Pellet, and some of the more fancy traditional looking rifles.
Depending on what kind of projectile you want to shoot will determine the kind of rifle to look into. If you want a true roundball rifle, then look for one with a 1-60 or slower twist. A 1:48 twist will shoot roundball, conical and even sabot. The Firestorm and PA Pellet are said to be great sabot shooters.
There are some custom rifle makers out there that will make you almost anything you want to shoot. Some of them are real works of art and are great shooting rifles...