I would definitely recommend Joan's place, it's central with ca 15 min walk to La Rambla and the metro 2 min walk from the apartment making it easy when getting around. Joan was a really great host, he gave us a detailed checkin at the apartment and gave us some history about the city as well. The apartment is two floors up on a smaller staircase but Joan was very helpful carrying our big suitcase up the stairs.
I could definitely stay here again when returning to Barcelona.