it is hard to blanket statement "best monitor" in a price range due to the very different needs of customers. one would need to cover each and every different type of customer such as gamers, office workers, media viewers, graphic professionals, etcetera. with how often the market gets updated with new models it would be rather difficult to keep such a list up to date.
the three main questions you should ask yourself are:
-what do i want to spend?
-is 120hz/3d important or is 60hz fine?
-what am i going to use this monitor for?
this will help you pick out what type of panel you should be looking for. after all we have tn, va, e-ips, s-ips, p-ips and h-ips. generally speaking this is a simple breakdown:
tn: cheap. this is also the only panel which comes in either 60hz or 120hz/3d. they feature fast response times but also have rather poor viewing angles.
va: i'm not very familiar with them but i do believe they offer a better viewing angle then tn. 60hz only.
e-ips: offer a wider viewing angle then tn but have a slower response time. 60hz only. normally i suggest e-ips unless 120hz/3d is required.
s-ips, p-ips, h-ips: these offer greater color accuracy since they can actually display more colors instead of trying to fake them like 6bit monitors. they are more expensive and have slower response times. they have almost a 180 degree viewing angle. i personally prefer these over the other panel types, even for games.
generally speaking gamers seem to prefer the lower quality tn panels since they are available in 120hz and that is what they deem important.
as far as brands go asus, acer, viewsonic, dell and all of the major brands are a good place to start. i would avoid any second rate companies.
led backlighting can save you money but quite a bit do not use white leds but use leds with a coating to simulate white. this can mean a blue-white or purple hue to the picture. more expensive monitors with led backlighting use white leds. there is no real performance gain between leds and ccfl at this time.