You also asked for preferences.
I own three flintlocks. A .58 Pennsylvania rifle, a .50 Southern Mtn. Rifle, and a 24 gauge smoothbore (trade gun). My preference is my Southern gun. Why? Because I like Southern Mountain rifles more than any other style. So that's what I want to carry most of the time. I built it on a .50 because I believe the .50 is absolutely adequate for deer; and that's the largest caliber/barrel configuration you can go, in my opinion, and still have the proper architecture on a Southern Mountain gun.
My .58 is the first gun I built from a blank... many, many years ago. I don't carry it so much now. Stylistically it has a lot of flaws, and they tend to stick out now when I look at it. It's a shooter though, and has taken three deer. The .58, with 70 grs of 3f proved itself to be quite a thumper on deer. I've also taken two deer with the .50; shooting 65 grs. of 3f. Of the five deer I've taken, only one still had the round ball retained in the carcass. It was one of the .50 caliber balls. The furthest shot was 60 yards, with the rest being 40 or under. No deer has traveled more than 30 yards. I haven't taken game with the trade gun. While it's 50 yard accuracy is just marginal, hitting soup cans at 30 yards is quite doable, and it's a fun gun to shoot when I'm in the mood.
If I ever build another gun for myself, it will be a Virginia styled rifle in .58 caliber; but I doubt that will happen. I don't want to put in the time and money for a gun that, when it's time to choose, would end up staying home. I have also owned a flintlock in .54. And, while many are fans of the .54, I find it to be neither here nor there. I just prefer the .50 or .58; depending on what I want it for.
If I only had one gun, knowing what I know now, it would be my .50. It's pretty, light, handles like a dream, and is easy to hit with. And I don't hunt anything larger than deer at this time.