Which monitor is better?

Solution
The Dell has more features, like USB hub and webcam. It also has the higher resolution, as you noted. Even though the Asus is LED-backlit, the Dell is brighter (300 vs. 250 on the Asus). The Asus does have a nominally higher contrast ratio, but a) manufacturers measure that differently, so different brands aren't always comparable and b) even if Dell and Asus measure them the same, both are high enough that I wouldn't worry much about it. Warranties are both 3 years, and reviews are positive on both. In the end, I recommend the Dell.
The Dell has more features, like USB hub and webcam. It also has the higher resolution, as you noted. Even though the Asus is LED-backlit, the Dell is brighter (300 vs. 250 on the Asus). The Asus does have a nominally higher contrast ratio, but a) manufacturers measure that differently, so different brands aren't always comparable and b) even if Dell and Asus measure them the same, both are high enough that I wouldn't worry much about it. Warranties are both 3 years, and reviews are positive on both. In the end, I recommend the Dell.
 
Solution