Personally I wouldn't put a tv above a fireplace. Wiring can be a pain, the space can limit the size, utilizing an alternate sound system (not the tv speakers) can be a challenging project, etc. Besides, if you have a mirrored frame, I would think that any room reflections (light, objects) would distract from your viewing experience. However, there is no right or wrong answer here, just my opinion fwiw. LCD or plasma would depend on your room lighting conditions (natural and artificial light).