Bitcoin is the mainstream choice. If you're looking for a cryptocurrency with first-mover advantage, unmatched popular visibility and the highest market capitalization, it's a no-brainer. On the downside, it's now nearly impossible to mine profitably, incredibly energy-intensive and, after rising more than 1,000 percent over the past year, could have expended most of its potential for growth. (This is debatable. No one knows anything.)

Litecoin offers its own advantages. Its creator is a known and active entity in the cryptocurrency community. It has a capacity for faster transactions -- a potential advantage in and of itself, which also provides for a different set of use cases than bitcoin. And it still offers the potential for profitable mining, unlike bitcoin