I started shooting BP in the 70s because that was the only way you could get a doe tag at the time.
I bought at least 5 TC Rifles starting with percussion and the last being flint. A good friend who was dieing from cancer gave me his custom flint longrifle, one shot and all my TC stuff was up for sale.
Bottom line, a fine flintlock is hard to beat, a run of the mill one will drive you crazy with hang fires and other problems. If you want a really great flintlock you have to get off your wallet as they have a $1200+ price tag.
If you decide to build your own there are three ways to go; a Lyman, TC, Cabala's or other assembly kit that you assemble and apply the finish with very little wood or metal work, a Track of the Wolf, Chambers or a host of other parts kits that require a bunch of wood or metal work, finish inletting and final wood and metal finishing, and lastly building from a block of wood and a pile of parts, lots of knowledge involved.
I decided building my own flintlock was a compliment to my bow building so I took the block of wood and a pile of parts route, never regretted my choice.
Just starting out I would get a Lyman plains rifle in flint to see if you like it.
Gotta' love those flintlocks, I have no interest in percussion now. the one in th picture goes off like a percussion gun and will shoot a tight cloverleaf at 50 yards. It is the one that my friend gave me.
This is the one I built, 54 cal and a mighty fine shooter.