@ig316b , That’s a bit of an open ended question?
Not all subwoofers are the same. Amongst other things, many subwoofers are ported as well.
Ported speakers have the advantage of providing more bass in a smaller box and/or more efficiently. However if one is pursuing more accurate bass, especially if time coherence is an objective ports, slots, passive radiators, etc., are a compromise. With the first order 6 dB slope used in most time coherent designs exacerbates this. With that said it’s quite remarkable that Jim was able to make ported bass speakers as well as most anyone at their price points and above, even compared to designs without time coherence objectives using more forgiving cross overs.
Still my preference is, for amongst other things: sealed boxes. In the past blending subs with main monitors was problematic.Things have advanced, and it’s much more likely to succeed in satisfactory blending today. IMHO, ports and their ilk as a design principle, should only be considered when space and/or finances are more limited.