The actual coverage of a antenna really only matters if it is outdoors.
When you use wifi inside the signals are bouncing off the walls and ceilings. This is why you will signal level difference if you would close the door to a room, the signal many times will bounce around and come though opening rather than try to go directly though walls. The signals bouncing off things and having slightly different delays is also what makes mimo work better.
In addition the signal pattern of the devices is not fixed with beamforming that is on some wifi equipment. It is a pretty useless feature but they do try to change the radiated pattern.
I would not put much trust in reviews. Most people have no clue what they are talking about. Even if there was some standard test you could run it means nothing. The house the devices are in affect the wifi performance much more than any difference between hardware. Pretty much every wifi review you see is a review of the house. Even many of the so called professional reviews are just done in some guys house and not done in scientifically controlled environment.