Ninjutsu: Kakashi
Taijutsu: Itachi
Genjutsu: Itachi
Speed: Itachi
Inteligence: Debatable, more or less even
Chakra reserves: Kakashi*
Stronger Dojutsu: Itachi**
*The whole "chakra reserve" thing is a dangerous game to play. A shinobi can have insane reserves, but if their control is lacking, they can lose to a ninja with less reserves than them, as the latter would use their chakra better and more sparingly. Anyways, I can see Kakashi having an edge. The amount of Kamui spamming done during the War Arc, coupled with Raiton use and other Ninjutsu puts Kakashi at an advantage, as far as actual reserves go. However, due to Itachi's impressive chakra control (considering just how many clones, MS techs, and Ninjutsu he was able to use before dying against Sasuke), I don't see Kakashi being able to outlast Itachi in a versus matchup riding on higher reserves alone. It can be argued, of course, but not based only on "he has higher reserves so he wins/outlasts".
**Kamui can be argued to be the "deadliest" out of the doujutsu being taken into account here, however Itachi's three main doujutsu (Tsukuyomi, Amaterasu, Susano'o) provide much more versatility and different applications, most just as deadly if unable to be countered, which would lead Itachi to be ranked above Kakashi in this regard.