Ported versus sealed speakers: is one type better?

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.  

bd24 is right but the result is that the ported design sounds as if it has more bass. Ported designs can be excellent such as Wilson's but the vast majority of them are colored. Designing ports is easy. It is just a math problem. I think where most designs fail is in implementation, cheap materials, resonant enclosures etc. 
I do not like any enclosure except for subwoofers. Open baffle speakers crossing over to subs at around 100 Hz work great. I use dipole ESLs
For subwoofers sealed is absolutely best. With signal processing and a very powerful amp you can make the driver do whatever you want. As long as the enclosure is inert you are in business. The best designs now are "balanced force." You put a driver in opposite sides of  sealed enclosure so that their vibrational forces cancel out. 
Infinite baffle design was mentioned. Bozak used Infinite baffle enclosures. This requires a large enclosure. Large enclosures are difficult to keep quiet. The bigger the board the more prone to vibration and resonance it is. Bozak used 3/4" plywood. The Bozak enclosure was a musical instrument. My father had a pair. With a Dynaco Stereo 70 they played very loud with rich chocolate flavored bass. They were colored as hell but to an 8 year old kid that system was the nuts.
In my own experience except for subs, the best enclosure is no enclosure.