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.