I like to consider the size of my elements of the blocks when I am choosing a border width.
For example, if I have a 3" size 9-patch block, then a 3" or 6" border may look more pleasing than a 4 or 5" border.
If my blocks have elements that are all 4", then a 2", 4" or 6" border might look better than one that is 3".
One inch stop borders look good with many sizes.