display tvs are shitty. they are out of the box settings, or worse, some dumbasses tweaking. Plus the input is usually a satellite signal split amongst 53 tvs or a DVD player hooked up with RCA cables.
The best thing to do is research the eff out of tvs online, reading reviews, visiting AVSForums, and armed with that picking the set you feel best meets your criteria. Once you buy it, use the calibration settings provided by AVSForum users to set it up to the "ideal" settings, and tweak that to your taste. I personally like a little brighter picture than most "ideal" settings provide, to each their own.
Comparing 2 tvs in Best Buy based on picture quality is garbage.