You can invest in both coins if you have enough money, But if you don't, then I suggest you should invest in Ethereum and other good altcoins since the prices has drastically fallen. Buy now, hold and sell when the market recovers.
ETH will not vanish, it's number 3 in the market now, just recently overtaken by XRP but with its big volume it will be back on 2.
Thinking of buying more at his moment, it has fallen already 10 times from ATH, so more chances to grow than to go down based on the average
and my own analysis of course.