Generally, the lighter the armor, the better the ratio.
Sometimes they throw in more leg armor and that is used as a "balance", but if you don't care about leg armor (which most dont) then you want to avoid the ones that have a decent amount of it, because most likely that extra leg armor was "taken from" the body armor value to make it balanced.
And yes, this is why Sarranid Guard Armor and Kuyak's are so popular
