Hi
i waited for years for either LCD or Plasma to be of decent quality, and finally i have bought a Panasonic 42" G10 plasma with 600hz and frankly it is stunning.
It depends on your budget, obviously if you can afford over a £1000 the Samsung o.l.e.d. are awesome but if you are looking for around £500 again Samsung plasma at this time really cant be beaten.
LCD tv`s are superb up to a point but if 42 plus is your wish, i have not come across one to date that has been anywhere close to a plasma in terms of picture quality. It is also worth really looking around, my tv was listed at over a £1000 but in the end i managed to get a superb deal from a local Panasonic dealer for £785 with a FREE 5 year full panasonic guarantee.....
However, the reality is research, look at reviews and shopper comments, because my experience at shops etc is that lighting and quality of input varies wildly and does not represent what you will actually see in your own living room. Each manufacturer also gives you completely different data to substantiate their greatness, so again you cant rely on specs, they should be made to have a standard benchmark...one day !!
Anyway, good luck hope this has given you something to ponder
Chris