It is partially subjective since in the ranker they put value on certain software features.
Part of the reason it get high rates in the speedtesting results is that it uses a very high clock rate cpu. There are other routers that use this same processor but since they do not test every router you do not see those others. When they do test routers that have the same cpu/radio and run the same clock speeds the routers have very similar performance.
It all depends what features you value. Can you actually use 4x4 mimo or can you use the non standard 160mhz support some routers have. This makes comparing routers very hard.
For example I was looking for a router that could do fast VPN. They do not rate routers based on that. Even the fastest router will be lucky to get 40mbps using openvpn. There is one cpu that has a special vpn accelerator that lets you get over 200mbps. The most common router people buy is the asus86u. You will notice this router is not rated high in their ranks because they do not put a value on vpn performance.
You also have to be aware no site is completely unbias they are dependent on advertising from some of those companies. Smallnetbuilder is mostly fair but they still buy into the hype that you need the biggest number. Why hook a $300 router to a 5mbps dsl connection.