At least, Ethereum is the number one altcoins in the market for now, but also remember that the crypto market is not stable, anything can happen. The coin ranking can actually swing to another coin/token, so any coin/token top others based on the marketcap increase or decrease at a given period on the ranking table.
Ethereum has in many occasions overtaken to the number 3 position at the coinmarketcap by Ripple (XRP), this situation may occur in near future.