Ranges are useless.
Many combinations of numbers that all fall within those "good ranges" will look much worse than other combinations.
It's complex.
It's math.
Since the numbers interact with each other you need to seek out the good combinations of numbers.
Tools like HCA and Idealscope do that.
Use them to pick a well cut round ... this and more is covered in the Advanced Tutorial.
A thin girdle is more subject to chipping than a thicker one.
The thicker girdles might be considered a waste of carat weight since that weight does not contribute to face up size.
I'd prefer a medium girdle but would tolerate a thick one if everything else about the diamond was groovy.
I'd avoid a diamond with a thin or very thin girdle unless it was going into a setting that protects the girdle, like a full-bezel.