I prefer bitcoin, because bitcoin has a larger community and the supply of coins is limited with a maximum supply of 21 million coins. But on another side, i also like ethereum because of the smart contract that has the potential to provide huge profits in the future. You can see the bitcoin and eth rank on the market, these two coins are equally potential as long-term investments. To buy coins depends on our capital, bitcoin investment requires more initial capital than eth, one of them by the fee of a transaction.