I've just bought a Panasonic Viera TXL32E6B from Curry's for £299.
I get a fantastic picture on this even with HD.
But then I've always got a good picture, even with the old LG "32" elephant in the corner" we bought twenty years ago, (reduced twelve years ago to the "second set") which was still going strong and had out-lived two others.
I have an old "recycled" 6ft dipole aerial originally used for 405 line TV transmissions. I put it the loft in the 1970s for my new, at the time, hifi tuner amp, it even has the old "thin" co-ax cable. I started using it shortly after for the TV as well.
I guess picture quality depends to some extent more about where you live than some of the TVs you buy.