What is the Best Tv? Oled, Lcd, Led, Crt or Plasma? Why?

There is no simple answer to this question….. it depends on your taste, how big of a TV you want, and how much money you have to spend…..
Old style CRT TV's have proven to be the most reliable……. but not many manufacturers make them anymore. LCD and LED TV's have the brightest picture, are the most expensive, but are unproven technologies. For my money, I wouldn't buy anything other than a Plasma set. For years, the Pioneer Kuro Plasma models were rated Best Picture by every reviewer in existence.
LCD's to me have an artificial look to them, like the pic is too 'digital'. LED sets look even better,
but I don't think the prices are justified. As with LCD sets, LED doesn't give you the viewing angle
that a Plasma set does. Go into any electronics store, look at the different models off-axis, you'll see the picture dim and disappear when viewed from an angle on anything other than Plasma.
There are hundreds of thousands of discussions and reviews on the Internet as to which TV is best..
CNet is a good source for initial reviews and provides basic explanations of various TV technologies.

Suggestion:

Best picture, probably OLED. Most expensive by a landslide… OLED. ($1100 for a 11" screen) The rest depends on your budget and your setting. If you have lots of windows, for example, you do not want a plasma as you will see the reflections of the windows better then the TV.

LED is an LCD TV. The difference is the backlighting. LEDs are used for the LED TVs and what amounts to fluorescent bulbs are used for LCD. Some LED TV's have steady state brightness. Some of those are Edge lit meaning the set is usually under 1 inch thick. Others use dynamic brightness meaning that they vary the brightness of the LED's depending on the picture. While this greatly increases the dynamic range of the picture, it does have potential problems. Stargate Continuum, for example, opens with a giant space scene so Dynamic LED sets turn off the LEDs so you can't see any stars. Plasma's don't have that problem. They also respond as fast as CRT's always did. The 600Hz figure you see with them was pulled out of someones keister. This figure is irrelevant to the picture.