As far as ported vs. sealed, from what I've heard... it all depends on the type of subs you want to put in the box. There are type of subs that hit harder in a ported box.. and there are subs that hit harder in a sealed box.
In general a ported box will give off a more low fequency base.
A sealed box will not hit as hard but the SQ will be cleaner.
What type of subs are you getting ?