I have the 27" because it's not too big and not too small. It's still heavy and awkward to move, but it's much easier than the larger sets. Mine is a Trinitron Wega. Trinitron refers to a technology used by Sony to produce a brighter picture. It doesn't have anything to do with HD. To my knowledge there is no 4:3 tube set that was ever made by Sony that is HD (above 480p that is). I could be wrong, but I've never heard of one. They did, of course, make several widescreen tube sets which I would not recommend using for playing older games.
In my opinion Sony produced some of the best tube TVs ever made in the late 90's and early 2000s. Mine is pushing 10 years old and has never had a single issue. Magnavox and Panasonic also made really great products around that time, but you're going to be hard-pressed to find one in the size/price range you're looking for.