I've used the older Asus 120Hz monitor (organge), two Samsungs, the older BenQ XL2410T, and other countless monitors that weren't 120Hz.
The XL2420T is the best monitor for me because of a few things other monitors don't have, or don't have all of. Height adjustment (I'm tall, and need it so my neck/back doesn't hurt), USB Hub (makes it easy to plugin peripherals when traveling, which I do a lot) and DisplayPort (120Hz on modern laptops and Macs, which I use for my gaming). The other features are cool, like be able to change the size of the screen on-the-fly, and Black eQualizer, though it doesn't really help for the games I play. Two HDMIs is nice for hooking up consoles and playing on a nice monitor, and no noticable input lag is always best. :P
If you have any questions, you can always contact me through the site, I will respond.