I've got a 720p Pioneer Plasma that I bought a few years ago.
At the time, Plasmas were superior to LCD's because of the whiter whites, the blacker blacks and the better handling of motion.
It's a kick ass tv. It was more expensive than an LCD, but it was also a lot better. No regrets buying it.
The drawbacks to it are that it does use a lot of power, puts off a lot of heat (nice in the winter) and is fairly heavy (but I don't carry it while watching it, so I don't really care how heavy it is).
If you own a plasma, you may want to unplug it when you aren't using it. Just having it plugged in still uses quite a bit of power. You'll be shocked at how much power a plasma tv uses when it is off.http://www.tvsnob.com/pictures/008_vampire_energy.gif
However, I've heard that today's LCD's have caught up quite a bit in terms of whiter whites, blacker blacks and motion handling.
When we add a tv to the finished basement, it may be an LCD...but I haven't done much research yet, so my opinion may change on that.
I know the new thing is LED tv's...I don't know much about them. I imagine they use a LOT less power and may last longer...and they are more expensive right now. Not sure on picture quality though.