The king of altcoin is ethereum, definitely. There is no altcoin can even beat ethereum and the coin which can bring change is only ethereum.
Of course ETH is the king of altcoin and has been on a top position among altcoin in the market since the start. Though it was replaced by ripple for sometimes but bear in mind that the market supply is not everything and you have to achieve so many other positions to outshine ETH which is not really possible. ETH is on position two in the market right now with the highest market cap among altcoin.