When Ethereum came out, it was looked down upon because the market hadnt matured yet. No one understood much about cryptos beyond the peer to peer transfer. When the difference between Bitcoin and Ethereum was established, that is when we had a surge of the altcoin rush. This caused prices to skyrocket on all altcoins. It seems as if the roles have been reversed and there is more doubt on Bitcoin than anything else. This is why we recommend you hodl Ethereum over Bitcoin.
Source :
https://usethebitcoin.com/will-ethereum-better-investment-bitcoin-2018/Etherum will be more profitable but being a better cryptocurrency is quite difficult as btc's goodwill is quite high. ETH price is comparitvely lower to btc so it's more prospective to invest into budget minded traders. Btc will reign for a longer period so it will most likely be the better investment in 2018.