As for me, I think the most overvalued coin today is Ethereum. I don't understand why does it cost so much. It is not decentralized. It is not limited, so there is no deficit. Nowadays it doesn't look innovative. It is not even great as a cryptocurrency. Of course it is great for ICOs, but most of the ICOs are crap. 
Most of this coins will die in future. So it's just a hype and nothing more.
I think that etheruem is an undervalued coin and it's value must be high.Etheruem has very good and fast network and is a good platform for the ICOs.I agree that most of the ICOs are shit but there are some ICOs which are good to invest in.And I think that Ripple, bitcoin gold and IOTA are overvalued coins. Most of this coins will die in future. So it's just a hype and nothing more.