the lowest brace that shoots well,, puts less strain on your bow,,
most bows will handle a higher brace and shoot well,,,,, but is may cause more set than you like ,,,
the lower brace will also usually have a bit better cast,, nothing dramatic,, but a chrono can detect it,,
if you want to brace your bow higher,, designing it for that would be a good idea,,
I think Tim Baker had a formula, that every inch increase in brace was the equivilent of drawing the bow 2 more inches,,something like that,,
if I am getting perfect arrow flight,, I feel like the brace height is good,, the arrow flight and the way the bow is shooting dictates the brace for me,,and it change a bit with the spine arrow I am shooting etc ect etc,,for example,, if you are shooting a lighter spine arrow,, a lower brace might work,, than if the arrow is a bit over spined,, calling for a slightly higher brace,,