Well at the current moment Itachi and Nagato are fighting Naruto and Killer Bee (who are both top tiers) and here are a few scans of Itachi fighting
An illusion or in other words a genjutsu. Now it also proves one fact. The notion that perfect jinchuuriki's are immune to genjutsu is false. They are not immune. They can fall for a genjutsu even if it is for a small amount of time. And here it took Bee five panels to break free of the genjutsu, which would be atleast five seconds in real time, which is way too much time for Tsukuyomi which is almost instantaneous. Even Naruto agrees with the fact that if Bee falls for Tsukuyomi or Amaterasu, he will be finished.
I know that the real battle hasn't begun yet, but still based on the current facts how high would you rate him.