If you want a good picture, you need a good video source.
Consider this: DVDs have a resolution of 480p. A standard HD TV has a resolution of 1080p. Forget about playing that DVD on a 4K set.
Here’s why that won’t work: when you feed a lower-resolution image into a higher-resolution TV, you get something called “upscaling.” Basically, the TV blows the image up to fit the resolution of the screen. This can lead to a fuzzy, distorted picture—and no one wants a fuzzy image ruining the crisp detail of Jurassic World’s dinosaurs.
If you have an HD TV, you want Blu-ray quality video at a minimum. Blu-rays have a resolution of up to 1080p, or even 4K in some newer cases, so they will take full advantage of the amazing screen you paid so much for.
You’ll also want to make sure your Blu-ray DVD player allows for HDR content (most do, but not all, so you’ll need to check). Just like with HD content, if your TV has HDR, but the input doesn’t, then the TV will upscale your movie for the HDR range, but it won’t really look like an HDR movie.
Lastly, remember you need ports to connect those inputs to your TV. You want HDMI ports, and plenty of them. These will give you the best input quality by far. If you’re getting a 4K TV, make sure it has HDMI 2.0 ports to support 4K sources—otherwise that fancy screen will be wasted.