Eth is the best coin at this moment, BTC would be like a "digital gold" and Ethereum should be considered as the "actual fiat money" I think that he should invest more than 40% on other altcoins.
I suggest you must have 30% eth, 30% btc and the rest for potentially altcoin coins. I suggest you have btc and eth as a backup coin if altcoin does not give profit but you still continue to profit from btc and eth. it's my simple investment strategy that I do.