ITachi because all he has to do is place Genjutsu on Minato "BEFORE" the fight, like he does with everyone else. And Minato would'nt even know he's in a Genjutsu. Then Itachi could just Could just kill him while Minato is unaware that he's in a Genjutsu.
The only way Minato would know he's in a Genjutsu, is if weird stuff start happening. But Itachi uses Genjutsu on you and make everything seem normal, like he did on Deidara and Sasuke.
Itachi will have Minato using FLying Thunder God and rasengan, in a Genjutsu, and Minato would be attacking an illusion, and he would think Itachi's dead. When in reality, Itachi is somewhere chillin.
Like as soon as Minato throw his kunai, BAM Itachi traps him in a Genjutsu. Itachi has a sharingan, so as soon as Minato throw the kunai, Itachi would have time. Plus if Minato throws a kunai, Itachi (Since he has a Sharingan) would see that seal on the kunai when it's approaching, and would most likely Jump out of range, or use Susano'o.
And also Tsukiyomi, which is most likely gonna be used. If Minato dosen't ever look in Itachi's eyes, how would he know that he's even fighting an Uchiha, or how would he even know he's fighting Itachi. Whats the point in looking at Itachi's feet when Itachi barely even moves in a match.
Now if Itachi finds out that Minato teleports to where his kunai is placed, then all Itachi has to do is use Amaterasu on an approaching Kunai, and minato would teleport to the kunai and get burned. ( Remember Minato is gonna be looking at Itachi foot, if he knows about Tsukiyomi, and if he looks at that kunai, that is approaching Itachi, he might meet Itachi's gaze and get caught. But this is not likely to happen.
I think Itachi might win.