set top box just need a screen to output video so any display device with video input will work.under 12k most monitors are TN but there are some ips panel from other companies too but no idea about their quality.anyway it is hard to find a good ips panel for ~12k so benq seems to the only option.you can at least use tftcentral review to calibrate it for increased accuracy/performance.
Are you completely sure that HD DTH will work via HDMI cable on that BenQ monitor. You mean no need of external TV tuner? There is also an audio jack in the monitor so would I able to connect it with my 2.1 speakers while watching DTH?
There is AOC i2353ph e-IPS monitor in my budget but according to TFT central review it has poor response time and input lag. Average is around 17.5 ms which I think would be not suited well for FPS games like battlefield 3 that i love to play. Is there any better model that this in other brands like LG, samsung, asus, dell etc? Keep in mind my budget is under 12k and its fixed. Many people suggested me Dell U2312HM IPS LED monitor but i can not afford that.