the design of the loudspeaker.

Jackfish is essentially right.

I personally would consider the sealed system, because it has a gentler low frequency roll-off, all else being equal.

On the other hand, a port can reduce the woofer excursion and hence lower distortion, with potential port noises (depends on design). Ported designs need a high-pass filter to roll-off the extreme lows so the driver is not totally unloaded at the lowest frequencies.