When investing, Im a big fan of diversification of portfolios. I believe that both Ethereum and Bitcoin offer value, albeit in different ways.
Even though Ethereum is positioning itself to become a large platform, the fact that Bitcoin is so well known makes it the first place where people invest.
It's a big mistake to trade your Bitcoin for Ethereum right now. Bitcoin is going to get segwit, and then lightning network, and then sidechains, and Blockstream just got Satellites out there to broadcast the Bitcoin Blockchain... so much exciting stuff happening in Bitcoin right now. I think everyone should have their main amount of crypto portfolio in BTC, specially right now, it's key to have as much BTC as possible.
Ethereum still has to overcome huge problems which im not sure they will be able to, meanwhile Bitcoin is sailing smooth, the only problem it has is the segwit2x morons being annoying again with the blocksize increase scam in November but we will get around that.
I, agree with Pereira as always BTC will stay as King of Crypto world. The portfolio should consist of both BTC and ETH as non-trading assets. You may have few ETH which you use it for buying rest.