For games 144hz does really make a difference. I would not even consider the Benq. Having said that you get excellent 144hz Benq monitors but this one is only 75Hz.
Also the AOC has the newer DP (Displayport) which is great to have.
True. If one is a hardcore or even a casual gamer 144 Hz is the way to go if you have a good enough PC. And I just realized the BenQ has a TN panel too, the only thing that would persuade me to go with a 60 Hz/ 75 Hz display is monitor that has an IPS-panel. It depends on if he has a good enough PC to handle 144 fps on games to get the full advantage of a 144 Hz monitor.