Well, it depends on people!
Theoretically past the 30 Hz, the human eye shouldn´t notice the difference!
But, i know of people that couldn´t stand watching a monitor at 70 Hz!
The best you could get its at 100 Hz (Any resolution!)
, just check and see!
The best monitors are from Sony! Depending on your needs you can buy a 17" G-200 (My own monitor! No words to describe it! Perfect image quality!), 19" G-400 and 21" G-500!
The best you can do , is going to some Computer Store and
see which monitor meets your standars!
Choose carefully because you are going to live with it for a long time!
Better burn in Hell with some company than freeze in Heaven all alone