I remember the days when Iniesta, Messi, Busquets, Pedro and others had game time on the first squad while they were young...
Busquets was 21 when he became, kind of, a regular. Pedro 22. Deulofeu is 19.
Edit: loan to Dortmund seems good tbh: http://www.totalbarca.com/2013/yout...rtmund/?utm_source=dlvr.it&utm_medium=twitter
I'd take Sociedad. They'll at least be in European competition next season and he'll get a good deal of playing time there.
Dortmund are not a small enough club to loan players to. They wouldn't need Deulofeu for anything but added depth and since he needs a lot of playing time to develop, it's not what he should be going for.
Rayo, Getafe, Sociedad, Espanyol, and Sevilla are all good options. Not low enough in the table for him to have shit teammates and not have a good atmosphere to develop, but not high enough for him to struggle to get playing time.
Loans rarely work.