Bitcoin is the most popular and trusted cryptocurrency among the more than 5000 cryptocurrencies in the cryptocurrency world. I think Ethereum is right after Bitcoin. The Ethereum platform is very popular in the crypto world, it is being widely used as ERC20 platform. There are also several other popular cryptocurrencies - Ripple, Steller, Neo, Bnb, Tron, CSTI, Monero, Eos etc.