It depends what your gonna use it for...
if your gonna game you want a decent refresh rate (16ms>refresh rate) these normally cost more, plus you wanna have a look at a few more things:
Brightness Ratio (450:1< i'd say)
Screen size (all are exactly what they say they are 15in, 17in etc.)
Resolution (because LCD's cant be changed like CRT monitors (1280 x 1024 is optimum))
Put all these factor together and you should always find a good monitor check the price along with similar makes and manufacters and your on your way...
I recomend the: Acer AL1715MS 17ins TFT (so cheap and worth it!)