first off people think genjutsu means automatic win if you are not uchiha, false as that would have meant that the uchiha would have wiped out the senju but they didn't. if genjutsu was so OP everybody in the narutoverse would specialize in it. genjutsu is not the end all be all, it's moreso used for distractions. most ninjas on minato's level will rarely eve get caught in a genjutsu, even if they are fighting someone like itachi.
izanami only works on certain people, and it sacrifices an eye. itachi wouldn't even use this on minato as it would be useless. the only reason he used that tech was because he was edo.
he's not hitting him with the totsuka blade, plain and simple, it's just not gonna happen. as for amaterasu, he will have an extremely hard time hitting someone as fast as minato, who is also a sensor.
so all in all minato is just as intelligent, if not more so than itachi. minato was considered by jiraiya, who was a powerful feared/respected ninja, as a once in a generation type genius. even with hax abilities like susano and tsukiyomi minato has a high chance of success. itachi can't use susano that long, as a matter of fact due to him have MS, all his MS abilities cause extreme stress on him. minato is able to make clones, who are also able to use FTG.
itachi is powerful, but in my opinion minato still takes this. his mastery of his techs are outstanding. itachi attacks a hard to land on faster opponents and minato is the fastest. itachi will have to resort to susano which will be his downfall as it will drain his chakra much quicker, and stain his eyesight. mid-high diff.