For me it will be Ethereum as it currently sitting at a market cap of over $132 Billion and a price of $1.2K as of January 2020. It enables the use of smart contracts that are executed after the right conditions are met and allows developers to create decentralized applications with no central point of failure. Ethereum 2.0 is an serenity upgrade that aims to bring beacon chains, Sharding, and Proof-of-Stake (PoS) to the Ethereum blockchain. Such changes will improve the speed and efficiency and also allow investors to stake their holdings and earn well.