Both of these brands have great 144hz monitors, though i would set my list as follows:
BENQ XL2411Z < ASUS VG248QE < BENQ XL2420Z
But it would of course also depend on the price of the different monitors, where i live the XL2420Z is a bit more expensive than the other two, therefore i would go for the ASUS one here, if you can get both the ASUS and the XL2420Z for the same price or very close to same, then take the Benq, only take the XL2411Z if you can get it at a good price difference from the ASUS one.
I think the XL2420Z is best because it has some strobe light utilities, have Benq's version of lightboost (which gives you a clearer/sharper moving picture), and the overall design of the monitor, which includes a kind of wired remote in the foot that you can extend out.
Hope this was to some help!