I would split the total: 40% BTC, 40% ETH and 20% XMR. Then you can use some ETH or BTC to buy low caps coins or ICOs
That is a reasonable choice, I also hold much btc and eth than any other coins since I treat them as a long term investment, I like to convert between eth and btc, I find it is very profitable, the ratio is much stable than the price, and I do not worry about losing any coins.
Yes, bitcoin and ethereum is a good choice for long-term investments in crypto currency. These coins are unlikely to disappear in the near future, these projects have come to the world of crypto currencies seriously and for a long time. Yes, the current market drop has hit hard on these and other coins, but it shows that at the moment prices have become very attractive.