It depends on where you are going to put the tv. Plasmas will render better blacks and have less flicker than an LCD. But LCDs will have better back lighting. So:
1. If you are putting the tv in a room that is consistently dark, plasma will render a better images
2. If you are putting the tv where there are windows or other strong light sources, LCD will be a better choice
3. A Plasma may use up to 30% more power than an LCD. Factor this into pricing decisions.
Extra Tip: If you choose LCD and you have a lot of focused light in the room, consider a screen with a matte finish over a gloss finish to reduce glare.