For me, as an investor, Etherium poses a bigger personal interest than Bitcoin, but it is pretty clear that at least for the next year bitcoin will be the leading currency in the crypto market. That is also because most of the people nowadays are familiar with Bitcoin, but have heard nothing of Etherium. But if you are looking for a long term investment, Etherium might be your solution.
It's not so easy to realise. You have to think the same way as the market will see these assets. And market over long period of time thinks that Bitcoin is the king. And even if we see that some coin has more and more usage and adoption it doesn't mean it will be number 1. If you remember few years ago people think the same way about Bitshares. But as we can see it's not even in top20.