Edo Minato > Base Minato >= Edo Itachi> Alive Itachi
Why Base Minato defeats every version of Itachi
Genjutsu counters
It has never been shown Minato's performance against genjutsu, but it was stated during the kage summit that Sharingan can't follow the speed of the likes of Raikage(compared to Minato) enough to actually catch the person in the genjutsu. Not only that, but now that we know he can use clone, all he has to do is to create one during the battle. Itachi can see handsigns with his Sharingan, but Sharingan can't distinguish clone with the original.
Genjutsu doesn't work on clone, so Itachi would have to make sure to be sure if the one he is facing is the clone or the original to try genjutsu. Sharingan can't follow teleportation speed, so Minato can likely use a clone during one of his teleportation during the fight and hide the original somewhere else at the same time. In this case, Itachi won't even know when Minato subtituated himself with a clone, fighting a clone with no hope of puting him in a genjutsu. He can even be fooled if the clone feint Itachi into believing he was caught by one so that he could blitz him when Itachi would try to take advantage of this to finish him(if he tries to cover the distance). But even if Minato doesn't use this strategy, but on the contrary uses a clone before Itachi's sight, as stated, Itachi couldn't identity the clone with the original, and judging by Itachi's intelligence, i think he won't try a clone before knowing who is the original and who is the fake. Not only that but even if he want to play gamble and miraculously manage to catch the original(on the contrary of the clone) in his genjutsu, the clone being capable to perform Hiraishin themselves could easily teleport to the original in an instant to disturb the chakra flow.
The clone may not even do it directly and wait until Itachi would close the distance in order to attack the original(while in genjutsu) and appear instantly to finish him(Itachi being close to the markings on the original's pocket).
But if Itachi fails and only put the clone in the genjutsu, it won't work like i've stated before. But if Minato wants, he could feint Itachi into believing it was fooled by the genjutsu only to take advantage of this if Itachi were trying to kill the clone(not knowing it's one) while closing the distance to destroy him
Combat advantage
Minato reflexive speed is so fast that it has often be compared to the likes of A or Naruto. He even outsped A's maximum shunshin by throwing his kunai above him(while close to his face) and outsped him before he actually traversed his kunai completely, from a decent distance caught infant Naruto who was an instant away to get impaled by Obito's kunai in an instant, crossed entire konoha in an instant to immobilise the Kyubi via Summoning jutsu, outsped even great shunshin users like Tobirama as well as the likes Hashirama(the supposed God of Shinobi). So a Minato alone is already difficult to handle because of his natural reflexive speed, but with another clone it will even be more difficult, especially since his clone can also perform FTG.
Good luck for Itachi to destroy them then. How could he even land a hit is questionable. As stated in latest chapter, his markings remain forever with no possible way to remove them, and since Minato is faster, if they engage in close combat, he is screwed. Itachi uses clone in offensive phase, so it's unlikely that he could use them and even if he does, until when? A clone remove half of your chakra and Itachi isn't a chakra monster. He would probably have to protect himself with Susanoo though
Only problem is that protecting himself with Susanoo would only make the fight last longer. Since he has no way to actually hit the opponent, maintaining Susanoo will be useless in the end considering the side effects of the jutsu.
It will even slow Itachi's reaction like Kabuto stated in their battle and more time will pass, more his speed, reflexes, stamina(and even sight since he has MS) will reduce. So sooner or later Minato will win, and that's even if Minato actually want to make the fight last that long. It's really questionable if Susanoo would even be that useful against Minato's arsenal. We've seen that underground is Susanoo's weakness thanks to Gaara who used the sand under Madara's feet, so by landing kunais or markings near the feet of the user, he should be capable to strike Itachi down in one teleportation, especially since the jutsu even has a radius
Further his superior summons makes up for his supposed lack of fire power if he feels the need
Knowledge
Itachi fans usually say that Minato has no knowledge on tsukuyomi, so he will get hit by it, but forget most of the time that tsukuyomi is only a increased form of Sharingan genjutsu. Sharingan genjutsu are well-known over the world for their dangerosity even by some stranger like Chiyo.
Minato has shown to have extensive knowledge on Sharingan capacities himself, to the point that to his knowledge only Madara could control the fox(knowing all Uchihas during his era as a Hokage), and even knew that if it was indeed him, he couldn't control him for long. He even has a contract seal that stops the sharingan control on the Kyubi, so clearly, it has been shown that Minato has great knowledge on Sharingan. So people who really think that Minato will engage any Sharingan(whoever he is) without taking precaution shouldn't fool themselves
On the other hand, Minato's abilities don't seem to be that well-known. Not even book-smart Sakura knew something about it and was totally surprised when she saw it in action. Not even his own most prominent student(Kakashi) knew about it until Minato decided to explain it to him personally and eventhen, they still didn't know about variants like FTG lvl2, space-time barriers, or subtle things like the fact markings never disappears. Not even counting Minato's other techniques like his sealing jutsus and so on, which are not even his base arsenal, so nothing even shows that Itachi has knowledge on Minato's jutsus, which could be the reason why this fight could last only seconds
I don't feel the need to explain why Edo Minato wins since it's obvious they aren't even in the same tier U_U