Currently using a Sony 40" which I got for free, before that a 37" LG, also free. There's plenty of people who for some reason want to get rid of their "old" television to get one of those newfangled "smart" things, have a look around the local classified ads/Craigslist/Freecycle/and you're sure to find plenty of options. As long as it has HDMI and a big enough screen you're set.
I use a ~16-year-old Samsung LNA52A550 (52", 1080p) that I spent rather a lot of money on once upon a time.
It has been calibrated for the colors to be as correct as possible. It's from a time before smart TVs. (Heck, it's from a time before LED-backlit TVs -- it's got fluorescent tubes in it.) But it has HDMI-CEC, and it cheerfully outputs both DTS and Dolby Digital on its optical TOSLINK port so as to connect to [cheap!!!, and sometimes even awesome] surround receivers of similar vintage.
If you find a Samsung of that age that hasn't been smashed, it probably won't work reliably as-is: They used bad capacitors in the power supply -- bad enough that they lost a class action lawsuit about that at least once.
(But good caps are cheap, and they're ridiculously easy to swap out on those single-layer PCBs. The only trick is to spend the extra few dollars and replace every single capacitor on the power supply board, and not just the ones that seem to be bad: All of the factory caps will turn bad eventually, which is something I learned the second [and hopefully final] time I took it apart to fix it.)
The two best TV's I've found at thrift shops are Panasonic Viero. One is a 32" in the bedroom and the other was 37" for daytime use in the lounge (for big pictures we use an old Mitsubishi HC7000 projector).
Both have great pictures, no dead pixels. The biggest issue with thrifted TV's is that they don't come with stands so you need to get a wall mount or contrive a stand of some sort.
I would heavily recommend against anything Samsung. There always seems to be something wrong with any Samsung being sold 2nd hand.