The market is changing at such a rate that the true answer to this question doesn't truly warrant a fixed answer but one that acknowledges a changing space.
Given that we're deep in the infrastructure-building phase of this crypto revolution - my strategy has been to invest in the platforms that are going to enable future growth, Ethereum, Neo, Lisk, Stratis, Waves and similar .
Here you can find some general answers to the most common questions about cryptocurrencies.