Concerning color vibrancy and motion blur, based on my impressions, Asus Rog pg279q has the slight upper hand in those two aspects

I fired up some DOOM 2016 to see how the response time and motion blur was and I can genuinely tell you that you will notice the drop in clarity and smoothness

On the rl2755, the AMA default is high, and it does such a good job of cutting down on motion blur yet preserving image quality, the likes of which no other 60hz monitor can quite replicate (some come very close, though, and it may be so close that it doesn't really matter for most people, but I have grown fairly sensitive to it in a game like Rocket League, where there's constant motion in the ball moving, car(s) moving, camera moving, etc..., and blurriness is terrible and makes things feel

this is it except for clear motion blur

the EL2870U is pretty good, but its high setting is just not as good compared to its 1080p rl27 counterpart, the only fix around is to set it to premium, which actually does a great job at cutting out as much motion blur as it can, but it visibly degrades image quality quite a bit

Motion blur was horrific

Most gaming monitors are all 1 ms response time (important to reduce motion blur), and their input lag tends to be around the same (10-11 ms for 60hz monitors, best it can get at 60hz), but how they go about handling motion blur can vary, Asus has a tracefree setting for example, and BenQ has their AMA setting