Rtings is also great for monitors. There's so much difference in quality and performance between visually similar display models and these are usually impossible to determine from official specs. I couldn't imagine having to buy a display without these detailed tests.
For my last major TV purchase, rtings.com was the most useful resource I could find for understanding the differences between options at the size I was looking for. They also have good roundups of the best overall TV brands¹, as well as regular roundups of the best options in several categories (size, primary use, etc.).
¹ https://www.rtings.com/tv/reviews/best/brands