We did the research and bought late last year.
The technology is moving fast - obsolete information may mislead! This may be obsolete...
At the time we bought, LCD was rated better on performance and power consumption than plasma. Reliability was also (according to the reviews) better - probably because LCD uses less power so dissipates less heat.
There were at the time three levels of picture resolution for the same screen size: 50 Hertz, 100 Hertz, and HD. We looked at all three in John Lewis's, watching the same HD DVD, and could see no significant difference on anything other than football (which we never watch anyway). The prices were about 2, 3, 4 units for the three, so we ended up with a 50 Hertz Panasonic, and it's been excellent.
The reviews also rated Panasonic well above Sony. I didn't do a load of tests, so can't confirm that. We've had it about 6 months and it's not even sneezed. We don't buy expensive extended warranties - the only time we did, the shop refused to honour it when we called it in. I mend most stuff myself, and reliability of quality electronics in our house has been good anyway.
We also bought a Topfield HDD recorder/PVR box which had its software tweaked (all downloadable). That is a brilliant bit of kit.
We don't play WII or any other games, so can't comment on those.