Kakashi wins low diff, mid diff at worst. With War Arc feats, he is faster, has better reflexes, better CQC. He can add Raiton to his taijutsu, with Raikiri in the hand or in his kunai, so his CQC can't be blocked or parried, just evaded, and that's difficult when he is faster and more skilled; Kakashi has also Rasengan and is better with bushinjutsu feints, he already fooled Itachi with a Kage Bunshin and can fool him everytime with a Raiton Kage Bunshin, even Pain with Rinnegan couldn't avoid to be tricked. Kakashi's other ninjutsu overcomes Itachi's easily, Raiden, Raiju Hashiri, powerful Suiton, versatile Doton and who knows how many other things shit on low level Katon and barely decent Suiton, and now Kakashi has the reflexes and speed to keep up with Itachi's handseals. Genjutsu isn't a factor, really. Kakashi has far more stamina and chakra and he is physically tougher, he can also open the 1st Gate.
In a all out fight, Kakashi's MS shits on Itachi's MS, as Kamui can outspeed Amaterasu, warp away Susanoo or Itachi in the Susanoo and be used without any risk to be caught in Tsukuyomi. Kakashi definitely surpassed Itachi. And that's obviously not counting DMS Kakashi, which is tiers and tiers above.