Welcome from the Northeast!
Here’s what I’d do … what era (when) appeals to YOU the most???? And possibly add where you are (North, South, west, etc.), and then pick a suitable arm from there, e.g.,
Late 1600s/early 1700s - Matchlock or doglock, depends ‘where’ your persona is
French & Indian War - French fusil de chasse 62-cal musket
Colonial days - Early, militia musket. Late, early Colonial rifle
Lewis & Clarke era - 1803 Harper’s Ferry flint rifle
Longhunter - Trade musket or rifle
Jerimiah Johnson/fur trade - Flint to percussion Hawken
… this is NOT an exact list, nor is it meant to be, but just to give you some ideas!
Then again, you might like some specific BP arm 1st, say like the Civil War era rifled-muskets of the imported British Enfields or the 1863 Springfields, where then you could decide ‘who’ and ‘where’ you are … if you take it that far. Some of us might just have a hat & maybe a shirt to shoot with our BP arms and just go shooting, and that’s OK too.
In the end … your options are wide open! Just beware this pursuit is ADDICTIVE!!!!!!!! And yes, the historical part also adds a HUGE interest to it for me too! Consider subscribing the Muzzleloader magazine.