Who benefits most from a DEF boost from a mod?

I'd say flat def mods on a low defense toon like Palpatine. QGJ might be the best example because he has decently high HP+Prot pool but naturally low armor. Defense also has diminishing returns iirc so while higher armor% toons might get more EHP out of each percent point, it takes a lot more defense to increase their armor. Would love to know the actual numbers though.