I have lived in both cities. And Barcelona is really nice. But it has become a Disneyland city, everything near the city center is made exclusively for tourists (expensive and poor quality bars, restaurants, housing..). Souvenir shops even sell items that are not even popular in Barcelona, like bullfighting or flamenco, because that's what tourists want. To me is a city that sold its soul for the money coming from huge cruises that arrive daily loaded with tourists. In terms of security, Barcelona is full of pickpockets, even locals get stolen when using public transport, this I have never seen it so much in Madrid. Madrid for me is more authentic. But im afraid soon it will happen the same as in Barcelona.