It is true that a poorly made 40" TV can use more energy than a more efficient, higher quality model's 50" TV of the same type. It is possible to make a plasma TV of the same size actually use less energy than a low-efficiency LCD model. And, newer technologies not yet on the market could prove even more efficient.
As a rule, however, LCDs use less electricity than a comparable sized plasma. You can get a sense of how much energy a set uses if you can feel how hot the monitor gets. My computer monitor, a LCD, gets warm at times but never hot. Most plasma sets get hot (as in enough that you risk getting a slight burn if you hold on to the hot spot long enough). That gives you an idea of how much energy a set uses. In general, the less heat a set generates, the less energy it uses.
There is a way to make a set use less energy. It also makes it last longer and less prone to burn in. Most sets come with the brightness and contrast turned up too high. Adjusting these to your home will make for less energy use, as well as making the set last longer. But I advise getting the adjustment kits from an independent company that has no financial interest in seeing your new TV conk out next year. Or, if you have some experience in setting them up yourself, you can try lowering the brightness and contrast yourself until you get the closest effect to natural. This also works on CRT sets with the same effect, though I am not aware of LCD sets with LED backlights having this problem.
Burning in on a plasma set is possible. They have gotten better about this in recent years, as well as more energy efficient. LCD sets likewise have improved with viewing angle and speed of refreshment. The CRT tube sets are still around, but they are more for smaller sets and may go the way of the Beta VCR and the turntable soon. I say that people should just buy the set that best meets their needs; if plasma improves its efficiency or LCD its viewing angle, the differences will close. And oLED sets, a newer technology, are promising to be even more efficient.
Besides, do you really need a 60" TV? If your living room is only 12' or 15', chances are you don't. That old 25" or 32" set might be ample if your living room is less than 15' deep. On the other hand, if you regularly have small parties and watch football, and the living room is more than 20' deep, then a huge screen TV might be in order. It pays to get the TV that best matches your needs.
