Don't really know about it but I think it depend on the amount of money you can spend to invest in is huge or not. For Ethereum from the early of this year until now it has increased from more than 8$ to 330$ ( about more than 3000%) and Bitcoin has increased from about 700$ to nearly 8000$ (nearly 1000%) so you think which one will be better? To invest in Bitcoin you need to have huge amount of capital cause the price of Bitcoin is too high but it's much easier with ETH, you can start with 1k$ only