A Sony Trinitron PVM-14L2 CRT Broadcast Monitor.
As the Nintendo 64 was developed when CRTs were commonplace, it depends on the unique characteristics of CRT displays to produce a good looking picture. The technology masked the imperfections. Modern LCD TVs use a software upscaler to resize the 240p input signal to 720/1080p and enhance the image, which is fine for motion video, but it does unusual things to console video input.
You can modify the Nintendo 64 motherboard for RGB or HDMI output with expensive and hard-to-source kits, with some soldering and cutting required, then connect it through a hardware upscaler and video converter…
… Or connect a CRT. And it looks incredible. Unfortunately it’s difficult to take an accurate picture of a CRT because of that whole electron gun refresh rate shtick.