LED OR LCD which is best buy

There are two kinds of LCD, one with LED and one without. The LED-kind has 2 subkinds: full and edge.
http://www.digitaltrends.com/home-theater/led-vs-lcd-tvs/ explains the details for a TV, but it's exactly the same with a monitor.

My advice: buy the one that gives you a good enough picture for your use. Read the reviews for each model on your shortlist and finally compare them in the shop.

Kees

All else being equal, LED backlighting is better than CCFL, but probably the vast majority of people wouldn't ever really notice the difference between the two. The primary difference is that LED backlighting is much more power efficient and some people claim it has a more uniform look to it, but if you're having to ask this question you're unlikely to be someone who'd notice the difference either way.

Once they come out with actual LED displays, not just LED backlit displays, this will all go out the window, but that won't be today or any time in the near future. So just go with whichever one looks the best to you.