Danzou takes this for the same reasons he takes any fight:KA...if i recall it's agenjutsu that doesn't need eye contact and the victim isn't even aware of being in an illusion wich is key in dispelling it...so KA>Tsukuyomi period and the activation time is the same,no seals nothing
As for izanagi i discard it cause it needs hand signs and for a fact itachi won't give him the time(tsukuyomi before he finishes them)
As i said danzou takes this...in a vs thread it's all about the jutsus not how much we like or dislike a character,for instance i kinda hate danzou and much appreciate itachi but i don't let my bias cloud my judgement