Vi Abrol :
my budget is $200 and 24" or 27" will be better if u suggest me something in my budget
Most of the asus monitors are pretty close in spec most different is ips or tn panel and i would suggest going with ips as ii have so much better colors.
If you want a 27" i would really suggest this one http://www.amazon.com/VX279Q-27-Inch-Screen-LED-Lit-Monitor/dp/B00DBVPOZG.
Its a little over your budget, but you may find them a little cheaper, i myself own 2 of these and i will buy a 3rd one once i sell my old 27" asus tn panel one.
I been extremly happy with them they have very slim bezels so they are great for multi monitor setups, and the response time is 5ms so you wont notice any ghosting or anything wit hthem, atleast i havent...