I’m going to go in a different direction that most of the answers, though I agree with a few of them.
Rather than trying to pick a 10000x winner (timeframe unstated), the real question is: which cryptocurrency will gain the most over the next three, five or 10 years?
Bitcoin (BTC) is still in its infancy: while most of us regret not putting $10,000 into $40 BTC, the fact is that the world is only beginning to be exposed to the new currency. Imagine being able to transport gold instantly to someone in order to pay for something: that’s Bitcoin. As new futures, ETFs, and equity-like vehicles begin to allow trading in BTC and drive demand, could we see an additional 10x, 100x or 1000x increase in value?
Ethereum (ETH) is the “corporate blockchain” (my term). While Ethereum is supported by major corporations, its currency also has significant value. It’s entirely possible that this CC could increase in value 10x, 100x, etc.
Litecoin (LTC) is designed to support high-transaction volumes (e.g., micropayments). While I have my doubts about LTC, its considered a mainstream alternative to BTC and could graduate to somewhat of a competitor.
As CC’s are in their infancy, it’s entirely possible that just a few will emerge as leading the pack. That’s my current take. Given the fact that so few people are even aware of BTC and ETH, I believe they are still viable for good — and perhaps outstanding — investment returns.