Contrast ratio is the most important aspect of a TV's performance. More than any other single metric, a set's contrast ratio will be the most noticeable difference between two TVs.
That is, if you could juxtapose them. Which you can't. Or if you could compare their claimed specs. Which you can't.
Read more: http://news.cnet.com/8301-17938_105-20066138-1/contrast-ratio-or-how-every-tv-manufacturer-lies-to-you/