I think Ethereum is definitely one of the altcoins worth investing in. In the past, I did not find it right to invest in any coin other than Bitcoin for the long term, but when I saw the thousands of developers working on Ethereum and some of the needs of the industry, I understood that it is definitely a valuable asset. Also, I think the important thing here will be the distribution ratio of your portfolio. If you think you have enough Bitcoin, it wouldn't be a bad idea to buy some Ethereum. 
It is proven and tested in these recent years, yeah it is good to invest where in the ETH is not badly beaten like the other coins when the market collapsed last year. The only thing that matters is when to invest, you cannot just buy Ethereum right away without knowing you cut loss levels, the margin that you will put and also your entry points. If you want to make money then we should be aware on those points that I mentioned, because those are essentials in a long run. Planning is crucial because it can help us to grow our funds and protect our capital in dips and retracements.