Memories. It would suck to not remember my family or friends, or having to re-learn all the skills I've forgotten, but ultimately that's still less harmful than the other options by a pretty large margin, IMO. I can create new memories and connections, and I have the ability to re-learn things.
Going blind and deaf at the same time would be super scary, and I wouldn't know how to get help because although I could probably find my neighbours or something, but they would either not have their memories, in which case they wouldn't know how to help me, they might not have their eyesight and hearing, in which case both of us would have a hard time communicating with the other, or they would have no limbs, in which case they can do pretty much nothing but speak, but that wouldn't really help me because I can't hear them. I guess a person with no memory and someone with memory, but no limbs could work together to help others, but if the amnesiac can't even remember language, then that's going to be difficult, too.
I do think that eventually humanity would get their shit together as amnesiacs re-learn things, but it would definitely be a major blow to the society, probably even leading to many deaths.