Ported versus sealed speakers: is one type better?

My experience with transmission line cabs is that they sacrifice midbass dynamics for bass extension. 

And no, efficiency is not solely dependent on the drivers. 

Transmission line enclosures are darn hard to design. Roger Sanders makes the best one I've ever heard.
I personally do not like deep base coming from my satellites. But, I use ESLs and cross to sealed subs at 125 Hz. 
I am not sure about this but I do believe it is harder to make a ported design operate below it's resonance frequency than a sealed design.
This might allow the sealed design to work better with room control. I have not used room control that way. I would always use subwoofers which might make the seal/port argument mute.  

It's all in the implementation

+1 End of story. Beware of the ‘expert’ who recommends any component over another based purely on genre.

Sooo much mis information posted in this thread.  Ported or sealed enclosure should be based on the individual driver(woofer) and its requirements. If anyone wants to look at driver spec's here are a few guidelines that will help you understand.  
I will describe 3 of these in elementary terms that are fairly accurate for easy understanding. 
1st Ported qualify's as vented, bass reflex, transmission line etc. 
FS.... a drivers low end resonance (how low it can go) hanging in free air.  In a few cases a driver can go below its resonance, but it is rare.  
QTS..... this spec gives you a good idea of what a woofer will need for type of box...... A low QTS requires a ported box to play any real bass,  Mid level QTS can go both ways, but will typically still go lower in a ported box.  Higher QTS typically likes a sealed box, they can port out, but would need a large box and can be boomy.  
VAS..... Gives an idea of how much back pressure or volume of air a box must create on a woofer to produce bass,  in combination with QTS,  we know how big a box needs to be for a given woofer.  
Every woofer has these parameters,  plus many others that are relevant in producing satisfying bass.    A QTS of .2 even with a low fs will sound more like a mid range in a sealed box, it must be ported to go down at all,  a QTS of .35 will still not go down in a sealed box, but can produce very satisfying bass when properly ported.  A QTS of .4 to .45,  I typically still like to port, but we are getting into territory where a woofer can go down in a sealed box.  A QTS of .5 to .55 is ideal for a sealed box.... when you get above .6 or so,  a driver can get boomy or harder to get the finished Q inside the box (QTC) to a respectable area.  
Another Fact that is easy to bend...... ANY WOOFER IN ITS PERFECT SEALED BOX WILL AWAYS REQUIRE A LARGER BOX FOR ITS PERFECT PORTED BOX.  The glory of ports is that they are very flexible in design and even though that bold statement is true,  you can get satisfying results from a ported speaker in a smaller box.  
Guys,  none of this is Opinion.  You either design a box and scour the earth for a woofer that will work in it,  or you design a speaker and build the box that it needs for optimum performance.... 
I hope this all helps,  Tim