Lmao^this dude
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The chibaku tensei is roughly 8x bigger than Kurama
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sasky's ct is as big as the bijuu
unlike nagatos
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The Kyuubi wasn't fully transformed,and you are exergarating on the size.Sasuke got all 9 full transformed Bijuu.Instead of thinking about the individual size,add up all of them and you see clearly Sasuke's is surperoir in both Size,and usage.
Nagato easily showcased the rinnegan better than anyone else.
The OP asked who has the better Rinnegan not who has showcased more.Nagato showed the 6 Paths - Madara and Sasuke have the potential to use the Six Paths aswell,and they are the original owner of the eye(s),so they can use it fully.
They both also have unique abilities for it,Madara - Limbo,Sasuke - Teleportation,and Sasuke can also use all his Sharingan powers with it.
------CT performance technique comparison----
-Nagato
single black orb as core,failed to capture half not even fully transformed Yang Kyuubi,granted Nagato wasn't in good condition,but even so it most likely would have beem a struggle.
Madara
-Multiple Black orbs as core capable of creating meteor sized CT in an instant.
Sasuke
-Uses the targets themselves as the core
-has used multiple targets as the core,and captured 9 fully transformed Bijuu in an instant.
Sasuke takes this.