Personally I use a Retrotink 5X, which handles every old console I own (NES, SNES, N64, GameCube) in visually lossless quality to my eyes. The built-in composite upscaler on a lot of modern televisions handles 240p as though it is 480i, leading to bad flicker. The Retrotink and other similar products upscales the signal properly, producing quite clean visuals.

framemeister, ossc and rgb mods

Do TVs not have composite input anymore? I haven’t bought a new one in forever.

Composite - no. But an adapter costs less than a good beer in most countries on AliExpress (well, shipping excluded).

Most of the ones I've seen do, but via an rca to 3.5mm dongle. The main issue is that the scaler built into most modern TVs does a worse job than even a cheap external one.