Just hold the top 15 at marketcap, for 15years are damn long...just hold Exp: ethereum , zrx, litecoin, bitcoin, neo,.
Neo are pretty good because you will receive gas too.. just make a neo wallet and store your neo at your wallet, you can claim gas as you want to. The yearly gas return abt 5% of your investments. And the gas prices also will increase too. Hope my suggestion this help you.