I'm going with Nagato for reasons I, and many other rational people have stated hundreds of times, probably within the same week (really this thread is over made).
I would also like to say there is no proof Nagato is weak against genjutsu. The senjutsu technique used by Ma and Pa wasn't the standard type of genjutsu, it was much heavier and stronger then normal. Tsukuyomi requires eye contact, which Nagato will know not to make against a shinobi like Itachi, and he only has ONE tehcnique that we've seen that uses genjutsu that is not dojutsu. Nagato has even used genjutsu to block the memories and secrets of his Ame shinobi and is probably capable of breaking most genjutsu, outside of the extreams (however there is no proof of that but there is no proof that he is weak against genjutsu). I'm just tired of people using the same genjutsu is Nagato's weakness so Itachi wins, excuse in these battles, because that is the only way they see Itachi winning.