Subwoofers: Ported or sealed?

Sealed and ported have similar efficiencies in the pass-band. Ported will go down lower.

All my experience and measurements say that the bigger issue is the amount of bass in a room. If you want to plumb the depths of bass with a sub you have to be careful of the placement and use appropriate room treatments and/or EQ as/if needed.

Smaller, sealed subs tend to leave the sleeping dragons alone. They don’t excite the room modes and therefore won’t ruin the sound. It is also true that below the tuning frequency, ported subs climb in distortion due to increasing exertion. They may also be significantly larger than the sealed counter parts.

I use a Hsu sub which has optional plugs. Whether I use them or not has to do with the in-room response.

Having said all of that, if we aren't talking about subs, I built a sealed center channel specifically because I knew I wanted to use it with a subwoofer, and crossing it over at 80 Hz or so would mean I'd get a lot of dynamic range and lower distortion in that configuration than I would otherwise.

Don't forget about passive radiators.

Acoustic suspended sub = Boring!

Ported = Bueno! :-)

For music, I much prefer low Q sealed. The roll-off much better matches the room gain so flatter to start with, and you don't need additional subsonic high pass filtering. Less group delay but I don't think that is really very important. 

If you are using DSP eq ( I suggest you do), the cabinet alignment may not be as critical. I like to start close and just hit the modes, so not giving up on sealed.  I run the DSpeaker box in line with the sub only on my stereo.  HT is of course done by the AVR. 

A passive radiator is a PORTED enclosure with the advantage of no port chuffing. The PR needs to be at least twice the area of the woofer to work correctly. Many are not. Very handy when the port calculations wind up with 8 foot ports. Down side is cost. 

For movie special effects where I want that crazy 20 Hz rumble, OK, I can see ported. That said, my HT is a pair of 10 inch sealed, Q .65 in push-pull and they can shake the house. F3 is around 30 Hz, so with room gain, they are almost flat @ 20.   My stereo is a single  12 inch critical Q (.5).  It does way more than I could ever use in my large open space living room for music. I don't do heavy organ or computer synthesized stuff. If I can feel tympany in my chest, that is enough.   Both systems are powered by a simple O-Audio BASH plate. No mega power needed. I know 1000W or so is popular, but you don't actually use it. Do the math.  I can do 95 dB with less than 1% THD with either system.  The HT does 102 dB before XMax @ 20 Hz. 

Not mentioned are infinite baffle.  They have quite a following. A DIY only. Finding a driver to work is not easy. I played with them briefly but found no real advantage. 

"Tight" "Accurate" "Dynamic"    Marketing BS.   It is the execution, driver, and crossover.   Or people repeating you-tube reviewers who have never designed speakers making up crap to fill a video. Any cabinet and speaker can be much, or sharp as a tack. 

The one absolute truth is:  Listen for yourself in your room. 

For music, I much prefer low Q sealed. The roll-off much better matches the room gain so flatter to start with,

This is a subject I don't think most audiophiles understand.  You have no idea what in-room bass response will be until you get the speaker in place.  In many cases the problem is too much bass and exaggerrated room modes.

you don't need additional subsonic high pass filtering.

Well, a subsonic filter can protect your speakers and reduce power demand, but sure.