Nothing, all TVs are crap.

The best options are usually buying large "monitors" or digital signage. However these both tend to be more expensive than a similar TV. Monitors also often lack a remote which may be valuable for a TV and digital signage may have less input ports than you may want.

I would love if a major manufacturer made a TV that just displayed what signals I put into it.

Right now the best option still seems to buy a Roku TV and never connect it to the internet. But some features will be disabled. For example Miracast doesn't work for some explicitable reason until you connect it to the internet. (Then again it barely works anyways, so no major loss)