Where you stay in Barcelona isn’t as important as the proximity to the metro system. The metro is very efficient and inexpensive. That being said Barcelona is a very walkable city as it’s generally flat. I’ll only take the metro for time critical appointments. Otherwise I walk. If you stay back toward Park Güell you’ll be close to the start of the Camino Catalan.
I don’t recommend El Raval as a neighborhood to stay in unless you’re very good about situational awareness as the rate of pickpockets etc is higher there and along the Rambla.
Let me know if you have any further questions