It's Kakashi's Susanoo, not Obito's. Look at the ****ing scar on the left eye of the chakra monster.
Anyway: Sasuke's Susanoo was raped not once, but twice, by Kaguya, with Sasuke put in danger. Kakashi's Susanoo managed to move quicker than Kaguya's giant form and to cut her chakra arms (remember that they was troubling Naruto and Sasuke) with his Kamui Shuriken. Everyone of them creates Kamui space-time holes that work instantly with a warp extended on the dimension of a Perfect Susanoo itself (
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). So basically Kakashi can spam like at least four instant and Perfect Susanoo sized uncounterable Kamui space-time warps at the same time, and at the same still use his other skills. Sasuke has more raw power with Susanoo Chidori etc but it's useless when Kakashi can spam four PS sized Kamui warp at the same time, use his space-time barrier while being in Susanoo, become intangible and blitz with Kamui Raikiri.