1. The {fact that it's not Europe}
2. The {People}
3. The {Wildlife}
4. The {Nature}
5. The {Spanish}
Barcelona is probably a really fun city, like if you're trying to only remember 40% of your time abroad, or if you're trying to learn a language that like three cities in the entire world speak. If you're trying to learn practical Spanish, America del Sur is the way to go.
Watch out for Chilenismos, which is a fun twist on real Spanish.