On higher difficulties (>Monarch) the most useful traits are Financial and Organised, as they allow you a chance of keeping up in the tech race.
Creative can be emulated by getting stonehenge, Industrious is rubbish cos you only ever get 1 or 2 of the opening wonders, spiritual saves the odd turn but is not a patch on the others, philisophical is ok but great people aren't as useful as more commerce from the two I chose. Aggressive is ok but not a game-winner