Choose flooring first then decide if you want to apint the brick , then your main wall color and IMO you do not need an accent wall that is your fireplace wall and peppercorn is very dark

Not a pro, but immediately thought upon reading your query that you don't need a painted accent wall since you have a lovely one with your original fireplace/paneling wall (lucky you!). A medium wood tone for the floor (don't remuddle with a gray tone)...pick up some samples and post pics next to your paneling and fireplace area for some input.

Accent walls were a fad that is now thankfully over, so please don't go there. Gray walls were another awful fad that everyone slavishly followed, although they certainly have their place. I would say not in your living room, though, with the warm colors of the wood and fireplace. A creamy color would probably be the safest choice, but without knowing your style or the furniture that will be in the room it's really difficult to say. A muted light blue might be another consideration, but as stated the flooring should come first.

^ what they said.