I think it depends on your offensive flow and quality of opponents. If you have good flow (i.e. good passing and handling ON EVERYONE), then slower offences tend to be better as your players will be able to find the open man and knock down better shots. If you are playing against a very good defensive team, then faster offences tend to be better as your players will have a difficult time finding a good shot and just jack it up at the end of the shot clock.