I would highly recommend staying at Francesco's apartment.
It is a great location, with everything you need within walking distance. The balcony is very spacious and provides a stunning view, with La Sagrada Familia featuring prominently.
The apartment itself is clean with all the amenities and comfortably fits someone (or a couple) in the bedroom and someone else on the sofa couch.
Francesco is very attentive and helpful and an excellent host.
All in all, a super base for a visit to this magnificent city.