I always steer folks toward Kibler based on the quality, service and overall value.
Cheap flintlocks are likely to be disappointing. Mass market locks for productions guns are a gamble. Locks made from castings and hastily assembled are not a good bet. A Chambers made Siler is going to be good. There are other custom makers. For now, Kibler is the sure bet. Those locks are made by CNC and are like a Swiss watch. I find my flints seem to last forever.
Mass market flint lock rifle may have a patent breech. Avoid that, they are not as reliable as a liner and regular plug.
As a club shoot target rifle I am extremely happy with my Kibler SMR's in 40 cal. I have two, identical, but one is caplock. I made the caplock-lock. One barrel is Rice, one is Hoyt.
The 45 cal SMR barrels are made by Green Mountain. They make a very light SMR. I have found that Green mountain barrels, on average give better accuracy than other mass market barrel makers.
I did find that the 32 cal was not as accurate as I wanted. That may be due to fiddley loading and or the barrel quality. Every barrel is an individual. My 36 cal SMR shoots fine, I do not know if it was GM or another maker.
You can not go wrong with Kibler. SMR, Woods Runner, or Colonial are all great rifles.