Among interior doors, pre hung doors offer the most flexibility. A pre hung door hangs on hinges within a new frame. If your old frame no longer works, a pre hung door is ideal. You can also use it to remove a door frame when making an entrance area bigger for an existing door.
The biggest advantage of pre hung is that they're weathertight. You don't have to worry about weather-stripping and making them tight-fitting. Pre hung also eliminates fitting the door into the door jam, ensuring it opens and closes freely.