Subwoofers: Ported or sealed?

Another option to consider is open baffle, if you have the room. I am really enjoying the bass from my open baffle subs, and prefer the bass quality compared to the sealed and ported subs I have had in the past. To me, it sounds much more natural than box subs - smooth, clean and dynamic, without pressurizing the room and without the boxy resonances that many box subs have. 

Open baffle subs have cancellation on the sides of the speaker, so fewer room modes are excited resulting in smoother in-room response. Also, since they don't pressurize the room, less bass energy escapes the room. 

The downside is that the drivers have to work harder to compensate for the cancellation between the front and back wave. If you like to play loud and/or have a large space, you'll need multiple drivers to play deep. They also have to be placed at least 3 feet from the front wall (although they can be very close to the side walls).

I use a stereo pair, each with four 12" drivers in a tower configuration. This is overkill, but results in lower distortion and smoother response. 

I've heard it stated that you can't get deep bass from an open baffle woofer. This just isn't the case. With Room EQ Wizard and a little bit of PEQ adjustment on the sub amps, I've measured flat response (within a couple DB) to below 20Hz, with the -3db point in the mid-teens. They can easily play WAY louder than I'd every want to play them. 

@phusis - I am currently crossing them over at around 180Hz. My main speakers are dipole line arrays which start to roll off around 200Hz, so this crossover point blends well. The sub towers with the plate amps I'm using won't play much higher than this. 

The drivers are made by Rythmik for GR-Research,  using a paper cone specifically optimized for open baffle. Each tower is driven with a Rythmik plate amp (HX800) which is built using two Hypex 400w amps, so the plate amp actually has two channels of output, each of which is connected to two drivers. These drivers have a second voice coil which is used as a servo feedback circuit to the amps. 

I don't think I've heard a tapped horn sub, but from your description I suspect the OB subs sound somewhat similar. They don't pressurize the room like a conventional sub - the bass is there in the room. For music from traditional instruments like double bass or kick drums, this sounds very natural. These instruments don't pressurize the room either. 

But if you are looking for that kick-in-the-chest sound, this type of sub is probably not for you. I wouldn't use them for home theater, for example, since most of the bass is from sound effects like explosions which you do want to pressurize the room.