While several cryptocurrencies can be used to access DeFi services, the scale of Ether (the cryptocurrency that powers the open-source, decentralized Ethereum blockchain) generally makes it the best crypto for starting your DeFi journey. It has the largest range of DApps, the largest user base, and the largest active developer base. Additionally, most of the popular Ethereum DApps have high liquidity levels which usually makes them faster, more stable, and easier to use.
By using Ether, you can also familiarize yourself with the specifics of how DeFi works by using a crypto wallet to manage your crypto and interact with DApps. Most DeFi ecosystems operate similarly, so familiarizing yourself with DeFi on Ethereum will give you the foundational knowledge you need to easily use DeFi on other crypto blockchains.
