Well to be honest with you, in order to figure out who would win, you would need to know how the fight would most likely start out.
The reason I say this because if we are doing Itachi vs part 2 Kakashi, then Kakashi would likely win before the fight ever started. The reason I say this is because Kakashi would have the advantage of not only knowing that he needs to finish off Itachi quickly, making him more likely to do so, but Itachi would not have knowledge of Kakashi being able to use Kamui to the extent that he can.
So with that being said, if Kakashi is armed with the memories of his last defeat, he'll most likely send Itachi to the other dimension right away, ending the fight. With Itachi still assuming he's dealing with a Kakashi similar to part 1, he likely wouldn't think to place him in Tsukuyomi right away, thus leaving him prey to Kamui.
However, those who are for Itachi can still make the argument that if he starts off with Amaterasu, then the fight is over as well, as Kakashi has not shown speed feats capable of dodging that attack. Even if he can, Itachi has already proven that he can get the better of Kakashi with high paced offense, as that is how he caught Kakashi off guard and defeated him the first time.
The only issue with that though, is that there is a higher chance Kakashi would try to use kamui at the start of the fight due to his fear of his last battle with Itachi then Itachi trying to use amaterasu or tsukuyomi right off the bat on an opponent he'll be under the assumption that he can easily do away with again.
As far as Totsuka, Susanoo, and Yata, Kakashi can warp a high-speed susanoo arrow, so he can likely warp Totsuka. But again he has been shown to lose to Itachi due to a lack of being able to keep up offensively, so Totsuka could end him if he gets caught off guard again. Since Kamui is a barrier (at least that's what the databook said) and not a real attack, Kakashi could Kamui Yata mirror away leaving it ineffective. Susanoo is still a mystery however, as it's not clear as to whether or not Kakashi could warp something that big.
I would say by playing the game of probability and taking all things into consideration, including how each fighter would feel going into the fight, Kakashi has the best chance of ending it early with Kamui. Itachi didn't use Tsukuyomi right away in their first fight, so there's nothing suggesting he would do so in another, especially considering that one tends to be more confident when fighting a foe they defeated so soundly, not less. But if we are assuming Kakashi doesn't try to end it quickly (which would be unlikely) and the fight gets drawn out, Itachi would then likely win due to having a higher powered offense and knowing that he can beat Kakashi with pressure.
I know you said you didn't want to hear this, but seriously it could go either way. I'd say Kakashi would likely win though as long as you aren't adding some crazy stipulation like the two of them not being able to remember their last battle. But really it's all about scenarios for this debate. Either one of them winning would be on a circumstantial basis, not because one simply better and could not be defeated by the other in any way.