I can't speak to the Asus, as I've never seen it, but I have a U2520D and it is an excellent display. Colors look great and color consistency is outstanding. Text looks reasonably good (not as crisp as 4K but wayyyy better than 1080p), the hardware/stand/hub is very sturdy, well-designed, and logically laid out. The cables included are excellent quality, and the included USB-C cable supports the 90 watts charging the display is capable of (and it's a good cable that won't fry your Mac). Device charging speeds are also very good. The 25 inch size IMO works really well with native QHD, especially for somewhat shorter viewing distances (if viewing distances are further, 27-32 inch might be a better match.) (You do get crisper text with a 25-inch QHD versus a 27 or 32 QHD display.)
It is worth noting that the hub data speeds are only USB 3.2 gen 1 (the 5 Gbps protocol), even if you use a 10 Gbps USB cable or a 20 or [passive] 40 Gbps Thunderbolt 3 cable to connect. Additionally, the data transfer speeds with SSDs are acceptable, but they are slower than if you plug directly into a 5 Gbps USB port on a computer.
Of final note, as you likely already know, there is a 27-inch 4K version of this display (U2720Q and U2720QM), which I own as well. Text looks crisper on it, especially small text, but both are really great designs.
