I was just at a site discussing this.
The first thing to know is how far away do you want to sit from the tv. Your tv, in inches, should be about 1/2 to 2/3 the size of your viewing distance.
So, for example, if you’re sitting 6 feet away, which is 72 inches, you’re tv size range should be between 36 and 48 inches.
If you want 40 inches or less, LCD is the choice. Between 40 and 60 inches, the site suggested LED or plasma. If you’re going bigger and are prepared to do the proper preparation work, projector.
Of course, it also depends on your personal preferences and budget and stuff.
We replaced our tube TV, gosh, 2 or 3 years ago at least, and I did calculations based on the idea that the screen should at least cover the old screen, with extra width of course. I think a rule of thumb is that you should go a step above that. It’s a new TV! Live a little! Plus, the larger screens do not represent the technological “stretch” that large CRT screens did. Also plus, when we bought ours the sales rep said that the most common buyer’s remorse was that they should have gotten a bigger one. Well, he might say that, but I believed him, so we went with the top end of what we had in mind. I couldn’t even tell you the inches right now. It’s a modest size in the range of what’s on the market ( which offers much bigger ones than a few years ago, ) but it seems very luxurious to us, even now.
Bottom line - get one with a bigger image than the old TV you’re replacing.