General Brazilian
assistiu, observou, vigiou
Most common usage; 'assistiu' for movies/TV, 'observou' for general observation, 'vigiou' for monitoring
São Paulo
assistiu, observou, vigiou
Standard usage consistent with general Brazilian Portuguese
Rio de Janeiro
viu, observou, de olho em
More colloquial; 'viu' commonly used; 'de olho em' for keeping an eye on someone
Portugal
viu, observou, vigiou
European Portuguese prefers 'viu' more frequently; 'vigia' also used for watching over