Okay,first of all
killer b is NOT breaking out of itachi's tsukiyomi,it takes one second to complete it's purpose,it would take more than that for hachibi to break bee out,so tsukiyomi is a one hit KO on bee if it hits. Sasuke's genjutsu is much much weaker than itachi's own,so please do ot compare them at all.
Bee reacted to minato's ftg as well as amaterase,IIRC he used a tentacle to block it,though he still got burned. He reacted to v2 A as well,while in base,however,not saying he is in the league of A in speed,but definately in his leage in reaction and reflexes. Also,in v2 mode,the chakta around him is the hachibi's own,which is powerful enough to block the ama flames if it hits,basically,the ama flames will hit the shroud instead of bee,and he will be fine,sasuke's amaterasu flames failed to burn through the chakra of gaara's sand,itachi's own wont burn through the chakra of the v2 shroud as well.
In a taijutsu/kenjutsu fight,bee is superior,and whuile itachi can hold his own against km naruto in a taijutsu match,bee is a different story and iIRC he pushed back itachi in base when he faced him.
Bee also has ink clones,capable of doing hachibi transformations as well,and can be a good distraction while bee preps biju bomb in his v2,also while in full susanoo,itachi's mobility is reduced,allowing bee to attack from blindspots more easily.
Healthy or not,it's still ms he has,and chakra drain will be severe as well as body pains.
For these reasons i'd say bee wins high diff.