OT: Now seriously, war arc Kakashi definetly wins.
Part 1 Kakashi is heavily outclassed with his below average stamina/chakra reserves and underwelming arsenal and current Kakashi is the same as war arc Kakashi except w/o Kamui.
War arc Kakashi is the most 'upgraded' version of his so...
Edit: I didn't notice the title was an actual scenario...
If you want to consider the same arsenal for both part 1 Kakashi wins due to the Sharingan's pre cog.
If you only count what he showed at the time current Kakashi wins due to better arsenal.
current kakashi has large physical strength and speed and more jutsus to choose from, as well as a almost limitless chakra pool now that no sharingan is putting drain on it.
however part 1 kakashi has the precog and raikiri/variants of raikiri.
i see this ending in a clone feint from current kakashi. suiton wave to push part 1 kakashi back, and then a final stab with a lightning charged kunai in the back.
keep in mind that precog is not everything. re read sasuke vs rock lee.
im not saying current kakashis speed is rock lee speed. but i am saying that current kakashi is the faster fighter physically.
I think Current Kakashi takes this, his stamina has quadrupled since the beginning of Shippuden and even at the beginning of Shippuden he had at least doubled in that aspect vs. Part 1 Kakashi.
Taking away Kamui only gives him more possibilities. Plus, Part 2 Kakashi is faster too, and stronger considering he can swing Kubikiribouchou with little difficulty.