Make sure that the HDTV models you’re considering are using the highest-quality video source that they can (HDMI, typically). Also confirm that the TVs are set to display video at 1080p. (These days, nearly all new HDTVs have that capability.)
Compare the ways different sets handle the same scene, side by side. Some televisions may make a dark scene look too bright, for example, while other sets might oversaturate the colors so that everyone ends up looking a little too thoroughly tanned or even sunburned.
This video comparison is also a good opportunity to try out a TV’s different preset modes, such as its movie mode, to see whether you can get a good picture out of it without paying for a professional calibrator or adjusting settings manually.
Photograph by Robert Cardin