General Brazilian
obcecado(a) com / viciado(a) em
Common in everyday speech; 'viciado em' emphasizes addiction-like behavior
São Paulo
obcecado(a) com / louco(a) por
'Louco por' is colloquial and slightly less formal
Rio de Janeiro
obcecado(a) com / doido(a) por
More informal and casual usage
Portugal
obcecado(a) com / marado(a) por
Portuguese usage; 'marado' conveys intense focus or fascination