depends on what your looking for. in general, a ported box will be louder and a sealed box will have better SQ. a properly built ported box can have great SQ also, but for beginners it can be somewhat difficult to achieve proper tuning. sealed boxes are very easy to build.
i made a vented box for 1 12 an its L 24 x W 19.5 x H 16 an the vent is about 2inches an from the hole of the sub its gos half way of the box an i got about 177watts 2 the sub an when it hits ur ears be popin nose ichin an ur hat vibrates its amazing for 177watts lol