That is more of a choice based on what type of contnent you watch, what your room is like, and personal preference!
Each has thier individual strengths
LCD:
LCD in general does better in brightly lit rooms with direct sunlight (Varies by model) due to the matte screens they have. LCD also has a fairly bright image. LED backlit models are very low power consumption.
Plasma:
Plasma is the display choice for move fans. They offer very very deep blacks, and the color is extremely accurate. Plasma does not have refresh issues that cheaper LCDs do. Plasma has issues in very bright rooms, as they have a sheet of glass on the front of the panel.
Here is a far more detailed explanation, and help chosing!
http/www.hometheater.com/content/how-choose-flat-panel-hdtvs