and its not only used for defense

*Eight Trigrams Palms Heavenly Spin- eventually there is either a break or stop in the rotation which the person can easily take advantage of the byakugan's weakness
*needles jizo- you are confined in a area and cant not move nor counter attack nor attack at all. If the enemy some how breaks through you are screwed =].
*shield of sand- okay if you really want to know the weakness to this one just watch deidara vs gaara there are many cracks in his defense. Any one who is pretty smart or is extremely fast can crack through his defense





*susanoo- absolute defense and can attack by using a eternal genjutsu. Although it takes an incredible amount of chakra from the user and also causes them to be in pain i took this pick as in asking which jutsu {meaning side affects dont count its just how well it can protect the user} is the most affective in defense and this one is even though it takes a toll on the user.

this one is good

susanoo by far!!!!!