No doubt to take the courses from LinguaSchools, cause they have the most creative and motivated teachers you are going to have lessons with.
And of course as a foreigner you would love to have quality time with people around you and the activities that arranged and well planned for you. So which will give you the chance to keep so many good memories and experiences during your education with LinguaSchools and living in Barcelona.
P.S. As a student that had the first half term of 3 months in Madrid, one of my concern about Barcelona was that the city is a Catalan speaking city. So depends on my experiences I would say that generally speaking Catalan in Barcelona is not a big deal while you are learning Spanish with Spanish Speaker Teachers and there are many ways to practise your Spanish by participating to events like "LanguageExchange" that happens in the city. Also public people are very understandable and able to talk to you in Spanish once they understood that you are a foreigner.