You must mean LCD or DLP. At up to 40" screen LCD direct is the best. As far as rear projection sets over 45" the DLP's generally have a superior black level to the rear projection LCD's. The best of the rear projection sets are probably the Sony 50" and 60" SXRD (LCoS) ones. Samsung will be releasing a DLP set that is backlit with LED, rather than the standard bulb. Backlighting with LED's should make the color palette significantly better and would also last considerably longer than the standard bulbs, which usually need to be replaced between 3,000 and 6,000 hours. The LED's are supposed to lat upward of 20,000 hours. I imagine the first LED bulb sets will cost significantly more.

At 40" to 50" the best sets are usually plasma's. The best of those are usually made by Pioneer and Panasonic. Vizio makes fairly good bargain sets.

Upwards of 50" you should try to compare by going to stores that carry rear projection LCD's, DLP's, and LCoS. Sony makes both rear projection LCD's and LCos (SXRD) sets. Samsung and Mitsubishi generally have good models of DLP's. You should check the black level on programming. In other words, does black look gray or like black. Also, you might want to check how off-axis viewing is. Many sets only look good with straight on viewing, but depending on the angle that you are off to the side, they can really suffer. Plasma's are usually the best at off-axis viewing.

Good luck.