In the fight between Naruto and Sasuke, we saw their battle. It seems that Kurama was more powerful than Sasuke's Susanoo (with bijuus).
Is Kurama more powerful than Susanoo? Yes, it is. From the wiki,
Even with half its strength, it could overpower Obito's controlled tailed beasts, smash Madara's senjutsu-enhanced Susanoo with a tail, and with the Six Paths Chakra, battle Sasuke's Tailed Beast-enhanced Complete Body — Susanoo.
That is just with roughly half its strength. At full strength, I would say it can easily overpower the aforementioned enemies, including Sasuke's Susanoo.
Remember that Naruto also used Senjutsu chakra during the whole fight (Kurama-Sage Mode),this could have enhanced his powers greatly but again it was only half of Kurama and some Tailed beast chakra within Naruto so maybe Full Kurama is stronger that Sussano.
However,it also depends on which type of Sussano Kurama fights.Sasuke's Sussano and Madara's Sussano were both "only offense" types so Kurama could overpower them.
However, Itachi's Sussano was completely different with the Totsuka Blade(and Yata mirror).One slash of the Totsuka Blade and Kurama would be sealed forever.Tailed beast bombs can be reflected easily with the help of the Yata mirror.And I'm not even talking about the perfect one right now.Kurama would definitely be no match for Itachi's Sussano.
I think that Kurama is an amazingly powerful tailed beast, and I think he's definetly stronger than all susanoos, but maybe he'd meet his first real match and that would be Itachi's susanoo, because once again, Kurama has only half of his power, and if Naruto and Minato somehow managed to fuse together and fight using Kuramas full power than maybe Itachi would be finished once and for all
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