I like Allders and John Lewis which although not necessarily always the cheapest, both throw in a 5 year warranty at no additional charge.They both offer good customer service(before and after the sale). It is of course important to look at a range of TVs in the showroom before deciding, although in my experience, alot of shops do not have TVs set up properly !
I bought a Hitachi 32" widescreen from Allders 2 years ago at a good price (cheaper than Currys/Comet etc), which developed a power supply fault about 2 mths ago. I phoned Allders, who sent an engineer the next day, but he was unable to fix on site. So it was collected, taken to their workshop, fixed and returned within 1 week. They could teach the PC industry a thing or two here about service!!!