click here Tomshardware and have a read through the reviews of TFT monitors.
Response time is not as important as some will have you believe! Some TFT's with a 20 ms response will out-perform one with a 16 or even 12 ms.
Look for a DIV connection as well as analogue, the DVI will give you a slightly cleaner signal, also look at the different types of TFT panel as some will give you a much wider angle of view.
The two main types of display are TNT+Film and MVA/PVA as used by Samsung Their advantage is very good colours and unmatchable viewing angles.
Remember that although you can alter the resolution to a small degree TFT's will always look better/sharper at their native resolution and for some people this can render text a little on the small side, not so much in applications but more so on the web, especially in web forums.
I'm using a 17" AOC TFT at 1280x1024 the display is razor sharp with stunning colour output but I do at times find the text in the forum a little hard to read due to my less than perfect eyesight. :o(