Generally, you'll get more SPL with a ported box. Most people would agree that sealed boxes are better for SQ, as you get much tighter, cleaner, and crisper bass.
I also think that ported boxes tend to sound a little muddy and fluffy, unless you have a professionally-tuned box (which I don't).
Ported boxes are also much bigger than sealed boxes. The average sealed box is under 1 cubic foot, while a ported box for the same sub can be nearly as big as you want (5 or 6 cubic feet, or more), within reason.
You can get good SQ from a ported box if done right. But you typically only get a 3db gain from sealed to ported. As said above sealed is smaller and have tight low bass. Nothing like an Eclipse Ti sealed. (although I love my ID Max's)