minato .
minato easily find tobis weakness while kakashi took a lot of time to figure it.
minato in just seeing it once found the weakness of kakashi's chidori while kakashi the owner of that jutsu was unaware of that danger, however kakashi was a kid that time.
jiraiya said minato is a genius, that the leaf haven't got ever since taht includes kakashi
Minato figured out tobi kamui weakness in a matter of minutes while it took kakashi 5 hours to figure it out but kakashi is smart considering how he figured out deva paths shinra tensei weakness but ill give this to minato