I track both Bitcoin and Ethereum very closely. Among them, I believe that possibility of getting highest returns is in Ethereum. Bitcoin has the first mover advantage. Being the first in cryptocurrency space, bitcoin will always dominate. But I think Ethereum has most use due to smart contracts and dapps. Ethereum have more chances of giving high returns. Bitcoin is a saturated crypto I believe. Bitcoin will also increase but due to its already high price, it's possible that percentage returns on investments may be lower than Ethereum and Bitcoin. Dapps are usually made on Ethereum blockchain. Building dapps on Ethereum is easy and fast. Ethereum has a strong technical community. Also most of tokens launched these days are of ERC20 type and are based on Ethereum blockchain.