I would buy definitly a Plasma it has the best contrast because you can switch of and on every Pixel thats just impossible for LCD. The LED Background LCDs are good but they have a big problem to show small things in a dark background like stars on a dark sky (they disappear if they are small enough) because they switch of all LEDs for a certain area. The best picture has Plasma the Contrast ratios are 100000:1 to 2000000:1 ( yes 2 Million) and the response time is 0,001 ms a LCD is atleast 2000 times slower (2 ms) but it dont really matter under 2ms. The LCD Screens have dynamic contrast ratios of 10000:1 to 50000:1.
The dynamic contrast can have sometimes bad sideeffects if you buy a cheaper model like a kind of pumping which is noticable if you watch dark scenes. The other advantage of Plasma is the color reproduction. They show the Color how it is almost as good as the old CRTs which are superior (in this point) vs LCD and even Plasma (a little). It has a wider viewing angle (178°). The Plasma itself shines so no need for background light like LCDs they have most of the time CRTs for light or now LEDs. So the Plasma are slimer (but the brand new LCDs with LED backlight are Slimer then the Plasma TVs an advantage unless you want to see stars on a dark sky). And they can be much bigger than LCDs the bad thing is that most of the people cant spend 20000 Dollar for a TV.
But the Plasma has also disadvantages. First they are heavier. The Display is always made of real glas because of that it reflects light more in bright rooms but the newer displays have an anti glare filter. The difference is really not that big with a new model. A big disadvantage is that you can burn in a screen, if you show an image a long long time (couple of hours). But the newer ones have Pixelshift so it cant happen. The other thing is the older ones need 4 times more electricity than LCDs. The newer one just twice as much. And the Price is (was) a disadvantage. They used to be more expensive. But the prices went down. Maybe they are a little more expensive but not that much. The lifetime used to be lower a little (but a lot longer then CRT TVs) but thats over the lifespan is as big as LCD TV.
I bought recently a Panasonic Viera TX-P46S10E for 1100 Euro.
Some stats:
Full HD
46 inch
Contrast: 2000000:1
Response time: 0,001 ms
Viewing angle: Infinite
Anti Glare Filter
Maximum number of colours 134 Billion
3 HDMI Ports you have 13 other ports (including a SD Card Port)
400 Hz
Even a gaming mode
And much more.
The difference between this and my old LCD is huge. They even have a smaller modell with 42 inch for 800 Euro with the same specs. Panasonic Viera TX-P42S10E.
I would go for Plasma if LCD. If a LCD then a Sony Bravia. The LED LCDs are thinner and they have a better picture quality but the technology behind it still has a flaw (really small objects on dark background) Most of the people maybe wouldnt recognize it but for me its annoying.
LCDs are gaining ground but plasma still have the best picture on the planet. No one would say otherwise.
