Yes, Ethereum is the best after Bitcoin. The popularity is very, very important for a coin to be successful. Ethereum is so popular and this is the main reason to be so good.
I agree that Ethereum is the best altcoin after Bitcoin and indeed popularity is very important, so that what makes altcoin can continue to grow is the community and popularity, so if the community of altcoin is strong, then of course altcoin will be popular and attract new investors to invest, an example is Dogecoin, because we know that currently the community of Dogecoin is very strong and that makes Dogecoin very popular, thus making the price of Dogecoin increase very high, therefore I agree that popularity is very important, so if one day there is other altcoin that are more popular than Ethereum, then of course these altcoin can replace Ethereum to be the best after Bitcoin.