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 is not bad to have both Bitcoin and Etherium in your portfolio. That is even better considering that Bitcoin is the leading coin in the entire crypto world and Etherium is considered second by many. Try to stick to these two on top of other trusted coins also.