This is an analysis of the 3 absolute defenses in Naruto, meaning that they protect the user from all sides. (note the susanoo in this thread is the non-EMS complete version)
Gaaras defense is a continuous/offensive wall defense. Although Gaara's defense has several weaknesses, it also has great offensive power since he can manipulate the sand to attack as well.
Gaaras Sand (auto-defense)
Pros:
Offensive capabilities
Always active
Protects from all sides
Cons:
Can be bypassed by very fast shinobi
Enough force in any area can break it
Can be broken by penetrating jutsus
Can be broken by a massive scale attack
The sand armor, while part of his defense, isn't as strong as the auto-defense, consumes a heavy amount of chakra, and slows him down considerably, making it a last resort if his auto-defense is ever broken or bypassed. It may help to reduce some of the damage for a short time, but in the long run it would hinder him more than help him.
Neji's is a continuous stationary rotating defense. It may be stationary, but since is a rotating defense, it can take much more damage than a wall type jutsu since the combination of ejecting and rotating chakra from the centrifugal forces reduces the impact and deflects the blows that are given.
Rotation
Pros:
Protects user from all sides
size and power of dome can be adjusted by the user at will
continuously reflects attacks
Cons:
requires user to spin to be effective
can be broken by drilling type jutsus
can be broken by a massive scale attack
takes a significant amount of chakra to use
Now the susanoo is the stationary/offensive wall defense. Its a bit like gaaras sand though with some of its weaknesses and those of the rotation
Susanoo(Sasuke/Itachi)
Pros:
protects the user from almost all sides
has offensive capabilities
size and power can be adjusted by the user at will
Cons:
user is susceptable to attacks from below
uses large amounts of chakra
enough force in any area can break it
can be broken by a massive scale attack
increases blindness in a non-EMS user
Susanoo is very powerful since it has offensive capabilities, protects the user from all sides and becomes more powerful with each added layer.
On the down side, it takes a heavy amount of chakra to use and can cause permanent blindness if used too much. It can also be broken with significant force and the user can be attacked from below or pulled out of the susanoo itself.
So its stationary, uses large amounts of chakra, and the power can be controlled like rotation, but has offensive capabilities and can be broken like the sand defense.
Now if we were to compare the most powerful versions of each defense strictly in terms of defensive capability, if would go like this:
1)Rotation
2)Susanoo(Itachi/Sasuke)
3)Gaaras Sand
Rotation overall is simply more powerful in many aspects than both the susanoo and the sand due to the type of defense it is and since has fewer weaknesses to break it.
If we were to compare them in terms of offensive capability it would go like this:
1)Gaaras Sand
2)Susanoo(Itachi/Sasuke)
3)Rotation
Gaaras sand can be used freely since this type of defense is automatic and is not restricted to being stationary like the other two.
Susanoo would be the in-between with both great offensive and defensive capabilties. It also has takes the greatest toll on the user since it not only drains their chakra, but can cause permanent blindness if overused.
