It is a personal choice of which AP to purchase.
like metro stated, if you live near the parks and go frequently, the preferred pass would be sufficient.
go and stay as long as you like then leave when the crowds come.
if you work during the day and only can go to the parks after 4, then the premiere pass allows you to use the express lines after 4.
it also has other perks for the holder.
it all depends on how you plan to do the parks.
go many times after 4 or go, enjoy the parks, leave when it is crowded.
if you follow the link metro posted, you will see the cost difference of the 2 passes.