I meant the dell would be better if you're only going to use it for light gaming(otherwise the asus would be better, though an hp zr2740w is better still).
The asus may have flicker because it uses PWM (Pulse Width Modulation) to dim the backlight, meaning the it's on 100% of the time at full brightness and 50% of the time when it's at 50% brightness. I think it uses 240hz for the backlighting so at 50% brightness it will flicker at 120hz. You need to get below 80 for it to become noticeable.
As for the calibration, I've heard (from tft-central) that it doesn't have a good default setup.