I would suggest Binance, as buying crypto is very simple. Just follow few steps.
Those who are short in money or would like to save, would not recommend Coinbase. As you first deposit EUR or US Dollars from your card or account, and only then make an exchange with 0.99 EUR fee (dont know about USD, as I make only EUR exchanges). For those who exchange huge amounts that is nothing, but for those who deposit 5 EUR, spending 20% of it on fees is irrational.