In my completely uneducated opinion (I've literally only started reading about crypto since I got that curie vote the other day), Ether is gonna be a bigger grower than BTC in 2018. But 9 years from now... Nope. No idea.

Diversifying evenly across the 5 biggest coins sounds like the best bet though. Not just to maximise chances of a hit, but also for damage limitation if any one of them tanks. Don't need to know much about crypto for that, it's just good sense. Similar concept as diversifying across Apple, McDonald's, Coca Cola, Toyota and 7 Eleven, for example.