I think Bitcoin is the king of cryptocurrencies. Eth is the queen. Ethereum with its smart contract as-well as decentralized nature has proven to be one of the most successful cryptocurrencies after Bitcoin.
We can call also ETH as a king but only in the altcoins market, and actually now, it's proven again that ETH is king because it's next to bitcoin now.
Check it now
https://coinmarketcap.com/, ETH is now at the no. 2, xrp was holding that spot for awhile but ETH is just strong enough, supporters will not allow it to be left behind, hopefully this year, it will remain in that spot.