As far as I know, now the best option is day trading, it is the most profitable if you analyze the course. But for this you need to have a good experience in order to manage to profit from this trade. If there is no experience, then you have to take a risk, or choose a long-term investment in cryptocurrency.
It's not easy to choose day trading especially in this kind of situation, difficult to get profits. In my opinion it's better to choose long term investment, I believe this coming 2019 the market will be rising again.