Need help with buying external monitor for work.

Hello everyone

I need some help here. Right now i have an Macbook Air 13" as my main computer, brilliant computer but the screen size is an issue if i am doing more elaborate work (in the screen department). I also have an Lenovo laptop.
I am looking for a monitor in the size range 15-19".

I do not play computer games, this is for work.
I prefer light as possible (perhaps LED is better?)
I prefer good looking designwise.
Price budget, i would rather pay more for better if its actually worth it.
It needs to be easy connectable with both my computers as a second screen.

Please recommend or if you have any importent suggestions or questions please let me know. Thanks!