This question has no simple answer. For me, it depends on the application and the drivers T/S parameters. Also, why stop at sealed vs vented?.... you can also consider folded horn and bandpass....
Each has its advantages sealed if your looking for good sound quality and would have less dynamic output, if your looking for boomy bass then ported. Of course each needs to be designed to match the driver's characteristics.
From a rookie like myself, how about this. If i wanted to but a all in one ready made box that will sound good without trembling building, but can be heard and heard good. what would you recommend, and where should I look?