Following up my first post as I said I would. As mentioned, I was quite indecisive between Rowlet (my favorite starter) and Cyndaquil (because of Hisuian Typhlosion's cool typing). I initially didn't really like Hisuian Decidueye's design, but warmed up to it and now I really like it.
Cyndaquil initially won out because of Typhlosion's typing, but soon after I chose it and played a little, I decided I really wanted to be able to travel through the main story with Rowlet as well, so I traded Cyndaquil to a friend to hold, restarted, picked Rowlet, and then traded to get my Cyndaquil. So yeah, I chose both. I was tempted to get Oshawott while I was at it since it seems to be the best for the purposes of the story, but I figured I can just wait and get it later.
I'm alternating my team around as needed, but yeah, Rowlet and Cyndaquil, which are now on the verge of being Decidueye and Typhlosion, are mainstays.