The Acer's monitor has double of the contract ratio of ASUS's monitor, everything else is pretty much the same. I never had any of Acer products previously, so I am kind of uncertain of Acer's image quality and features.
I own the ASUS VG278H and would highly recommend it.
The ASUS has newer technology than the Acer and is better overall for 3D between the two because it uses lightboost. Lightboost modulates the backlight of the monitor to increase the brightness of the percived image and reduces crosstalk between the left and the right image (basicaly it means you see less of the left image in your right eye and less of the right image in your left eye).
With 3d Vision 1 everything looks a little dim while using 3D but with lightboost and 3D vision 2 it is much improved.