I've just looked into this before buying my new TV; plasma and LCD both have their pros and cons. They both offer larger screen sizes and take up less space than smaller CRT TVs, and, if you watch a decent source, offer fantastic picture quality. Make sure you buy one with the HD Ready logo as Sky start broadcasting in HD in February and hopefully others will follow suit.
Which one you go for is down to personal preference, look in the stores at what is available - though it was difficult finding stores that could demonstrate them properly with a decent source. I went for LCD as I was worried about screen burn with plasma and am very pleased with my Sony.
An interesting forum is http://www.avforums.com/forums/index.php
which is very comprehensive and has all the info you can shake a stick at - if you've got the time to search through it.