Best flat, right in the centre of Gracia. We were there during the Catalan referendum which was an amazing time to go.
The flat is in the middle of two squares where the community gets together, so there's no lack of atmosphere. Walking in any direction you'll find cool bars, and it's not far from anywhere - Park Guell, the Gothic Quarter, or La Sagrada Familia are all down the road.
Joana is a lovely host, very friendly and gave us detailed information about places to explore.