They both have attacks that can actually take each other out of existence, but Kakashi's would suck more.
At least you get to dream in Totsuka Sword, but being stuck in another dimension would be worse than being in prison.
Itachi wins, only because he has more mastery of Totsuka than Kakashi does of Kamui.
I am aware that Kakashi did warp a nail and Susano'o arrows, but Itachi WTF pwned Orochimaru who was looking directly at him with Susano'o.
Not gonna mention Nagato, because Itachi technically did have help, even if it was just using Nagato tearing up Naruto and Bee as a distraction.
ABOUT THE ARGUMENT OF INFINITE CHAKRA FOR EDO TENSEIS.
I do agree that being an Edo gives you more chakra. Since you are constantly regenerating your body, it would stand to make sense that you don't experience exhaustion as you would in a "physical" body, but chakra is also made up of "mental" energy too.
I feel like this would mean that even though your body is physically regenerating yourself, unless you have your personality erased your "mental" chakra would also drain, which would still drain your chakra, but less so.
It's possible that the reason that Ao can sense huge chakra levels is because it's likely you cannot go past your regular chakra level while in Edo form, but it regenerates to an extent because your physical energy doesn't go down due to constant regeneration.
It's like when Ao sensed Kinkaku and Ginkaku vs. sensing Itachi. Kinkaku and Ginkaku had high chakra while alive, but it's not infinite. They're probably brought back with the chakra they had before they died, and cannot go past the plateau Itachi has less than them, so he wasn't as noticeable to the Sensor department.
Your average Edo in the war would be able to outlast ninja with high chakra levels that are alive. It's the skill level of the alive ninja either surpassing or being more powerful than in general that allows them to be sealed.