When i bought several LCds i was not well informed. All i can tell you is that Plasma had a bad reputation (heat and power consumption). The last LCd i bought was a Local Dimming, xbr8, which is a ''good enough'' TV till OLED becomes affordable AFAIK.
btw its is not whats best, its about whats good enough and what works for you. Even on AVS most folks do not own a top TV. The top TVs right now are UN85S9 (4K), KE55S9C, and the 55EA9809 because that is the latest in high quality what TV tech has to offer.
In addition to the reasons already stated by others, heat was a big issue for me. My Pioneer Kuro would really heat up the family room in the summertime... Another reason is size limitations. I replaced the 50" Pioneer Plasma with a 70" Vizio M Series LED. No regrets whatsoever!