The BCA league will be an easy way to start with no committment necessary. It's a league that is designed more for the few higher level players in your area. If at some point the league grows and becomes successful, it is also just as easy for someone else to startup another BCA league to compete against the leagues you've started. And all of them to be able to go to the same national BCA tournament aforementioned.
If you can handle the APA startup fee, The APA league is a better fit for a smaller town because it appeals not only to the higher level players, but to the medium and beginner players as well. All skill levels are necessary for an APA team. Whereas a BCA team can consist of the 3 best players in your area. With that structure, then there's virtually no reason for other players to even try to compete unless they are clear they are battling for 2nd. Whereas in the APA, the 3 strongest players would have to be spread amongst 3 other teams, if they want to play. Also the APA has so many more offerings for intermediate and beginner players, including (amongst a wide variety of others) a singles tournament (8 ball and 9 ball) tiered for advanced, intermediate, and beginner levels. Each tier competing for $15,000 (8 ball event) for first place. Surprisingly, the beginner level has about 20 people competing in the National tournament, providing excellent odds in their favor. Simply stated, it has many incentives for bringing in new players, which will be critical to success and expansion which is vital to staying afloat in a small town.