Contrast ratio, warrenty, price, max/native resolution and brand name.
Average is around 450 to 550. The higher, the better, but 500 is good.
LCDs are prone to getting dead pixels. Make sure you get a good warrenty.
There is good quality LCDs available locally for around $300-$400 CAD.
The max resolution is pretty self explanitory. The native resolution is the resolution that the picture looks its clearest. THe LG that I am on right now has 1280x1024 max resolution and native resolution.
Everyone has had their good or bad experiences with LCDs and certain brand names.
I personally dont own an LCD monitor. I am on an LCD right now at work. It is an LG1710S. It has really good picture quality, and is nice and bright (but adjustable).
Is the measure of how long a display takes to change the image. You're right, the lower this number is, the better. But, the lower this is, the more expensive the monitor is too. 12ms is good for games and everyday tasks and isnt too expensive. There are 8ms, but they are kinda excessive.
Hope that clears some things up