The first thing I'm going to do is disagree with you, but don't take offense, hear me out...
If you are comparing factory built flint rifles with factory made percussion they I guess you are right, percussion is more reliable...
I have never owned a percussion, nor have any desire to...
I have never owned a factory made flintlock, nor have any desire to...
I bought my first muzzleloader in 1977, a custom made flintlock from Bob Watts in Stone Mountain, GA when I was 23...I have used this rifle ever since and it is deadly accurate and very reliable...
I build a .54 caliber flintlock in the late 80s and have killed at least 50 deer with it, never had it not go off while hunting...Ignition is very quick and with 80grs FFF Goex I have dropped deer in their tracks out to 125 yards...The ball almost always exits and leaves a nice blood trail for tracking if needed...
Both of these rifles have cut rifling .015 deep for shooting round balls...Most factory built guns have shallow, button rifling about .006 deep...This is why they can be finicky as far as ball/patch combination and powder charges...
My .40 is acccurate with 25-70grs FFF Goex...The .54 with 40-120grs FFF Goex...Both have Siler locks and send a good shower of sparks into the pan...Both have coned touch holes located at the sunrise position so you can fill the pan and not fill the touch hole with powder...
With both, if your powder is dry and your flint sharp they are going off...Fast, reliable, accurate...
The problem with factory flinters, often the touch hole is not located properly, the frizzen is too soft or hard, the main spring and frizzen spring have to be tempered properly as they work together...The barrels aren't the deep cut rifling you have on custom guns, etc...
So, if looking at a factory built flintlock the only two I would consider would be T/C or Lyman...I would want to inspect it first to see that the touch hole is in the proper position and see that the flint sparked reliably with black English flints...
Better yet...Save your money and order a high end kit from Jim Chambers...
Remember, the flintlock ignition system was invented around 1600 in France...It was in constant use for almost 250 years, right up to the beginning of the Civil War, longer than any other ignition system available...
It's all Daniel Boone ever knew...It's what Lewis & Clark carried across the country and even though David Crockett was given a percussion rifle at Philadelphia during his tour in that area, he elected to carry his reliable flintlock to Texas....