Which of these 3 touchscreen monitors is best?

I'm in the market for a touchscreen and need something reliable. I know that the most reliable monitor is a non-touchscreen, but I really need to have a touchscreen for the application I'm using it for.

http://www.tigerdirect.ca/applicatio...854&CatId=1449
http://www.tigerdirect.ca/applicatio...415&CatId=4420
http://www.bhphotovideo.com/c/produc..._21_5_LED.html

Any thoughts?