It really depends on what you are going to be doing.
If you don't really game you don't really need an extravagant expensive monitor, and should only really look at size and resolution, also if you don't have a good graphics card, chances are you will not be able to use a really high resolution anyway.
If you're really into gaming and have a good graphics card that is capable of using higher resolutions, while maintaining a high quality of detail in games as well as framerate, then by all means choose a monitor with a high resolution and good response time.
As far as the refresh rate goes, I've pretty much always used 60hz and have never had any issues or complaints.
We would probably be able to help you more if you were to give us some more information about your your graphics card, and what games you would be playing just to get a bit of insight of your situation.
Hope this helped!
"You have a big word for a guy who don't have a gi right now." - Renato Laranja