BTC and ETH are not even in the same neighborhood. If any coin is overvalued during this crazy crypto pump across all coins, the winner is surely ETH.
Realistically speaking it should not be valued for as much as it does.
Based on what? The fact that its risen so fast? Its a fact that a lot of ethereum is now effectively locked up in various ICOs and the demand for ETH to pay gas fees is rising at an enormous pace. The demand for bitcoin however I feel is more speculative since you don't actually need it for anything, except maybe to buy altcoins on exchanges.