After seeing these two fight briefly in the manga I give this to Itachi.
When Killer Bee tried his sword dance on Itachi, Itachi stayed on the defensive and protected himself w/o getting a scratch.
His genjutsu was hindering Killer Bee a little, enough to at least create a potential opening in their fight.
Tsukuyomi ends KB, it lasts 1 second which doesn't give Hachibi enough time to break KB out of it.
Going full BM Mode makes him more vulnerable to Totsuka due to size, not to mention he had to last second escape through the tentacle.