Conquest is a waste of time in most cases - as Domination occurs much sooner under the same principle. Culture is boring, but nice if you don't like to war. Space race is unrealistic (I still say it should be planetary, not stellular travel), and seems to only work if you're way ahead - in which case, conquering a few cities is enough. Guess the map size is a factor there. Diplomatic is foolish as it's an all or none try that can be exploited due to the way it's set up.
I don't like any of the victory conditions, so I usually play until I am satisfied with my result (or admit defeat). I guess points reflect this best, but long before the deadline I give in and quit or change to domination just to get the win. Hopefully they come up with something better in round 4.