We keep on having to debunk this nonsense. It's true that port output is a cycle behind the driver, but many of the subs on this list are all tuned too low for that to matter. The tuning frequencies on these subs hover around the lower end of the frequencies that human hearing can discern. Very little musical content lay below 30 Hz, and what musical content does lay down in that range isn't going to suffer much from the group delay of ports. Most sealed subs are totally inadequate for attempting to reproduce sound in that range above a quiet level since the driver is quickly pushed to its excursion limits in deep bass and can produce lots of nonlinear distortion which is much worse than the phase distortion of ports. What's more is that most sealed subs that are available have protective high-pass filters on them which hike up group delay in these lower frequencies anyway, not that it matters much in terms of audibility.
Basically, there is very little reason to go with a sealed subwoofer over a well-designed ported sub for any type of content.
With no due respect, you don't know what you are talking about. If ported designs were so great, sealed or dipole subs wouldn't exist anymore. The sealed Rythmik subs I use are 110° out of phase due to the low pass filter at 20Hz. No ported design can do that.
Having 4 of them, the dynamic range is more than any human can take in my basement when it comes to music. Add in that they are servo subs and the bass is even cleaner than a standard sub.
As to there being little musical content below 30Hz, you are right unless you are talking about pipe organ or taiko drums. That doesn't mean that the port tuning and the sub's low pass filter aren't screwing up the temporal response of a low B note (31Hz). They are and quite badly. With the lower port tuning and the steep high-pass filter, OK, the bass fundamental sounds like it's 40 or 50 feet behind the initial pluck of the string. As a bass player, that's not nearly good enough for me.
If you don't mind your system being delayed by a 100ms or more, then you can use DSP to get the port in temporal alignment with the higher frequencies. It will require some serious processing power, but it's absolutely doable.
HEDD is doing this with studio sub/sat systems. Yeah, you never heard of them.
So, again, having owned mostly ported speakers and subs my whole life and done a lot of experimenting with both types of designs in the last 40 years, not only do I prefer the sound of my music and basses from sealed, servo subwoofers, every metric you can use will prove out my preference.
Again, the only downside is that you need more subs since ported designs are more efficient at their port frequency.
We haven't even gotten into port noise as well as the ringing that ported cabinets also exhibit.
Let me close with this: having recently bought Prince's "Sign 'o' the Times" Blu-ray, I was stunned by the low end of his song "HouseQuake". The concrete slab in my basement was massaging my bare feet. I never experienced that before. Talking the grills off of my Rythmik subs, they were creating the incredibly low, single pulse of the kick drum and then just stopping. I've never seen a sub driver do that before. Usually there's a little "flobbing" around as the driver meanders back to center. Not here. Rarefaction, reaction, and back to center.
I was quite impressed.