• The ones with a use cases
• The ones with an established history
• The ones with unique features
• The ones with transparent development

Fact is, it requires ton of times and specific knowledge to check the previous poins.

As far as I'm concerned, I'd go with a portfolio of about 80% BTC, that I'd be reasonably sure to increase it's value with limited risk over a period of 5 years.

Maybe some unknown alt-coin may turn me rich in one night's time, but risks are huge; I'm not willing to invest my time, nor I have the knowledge, to look for the next crypto shooting star, and I'd advise anyone not to.