ETH or BTC will be a good solution for long-term investment. These two coins will continue to grow given that Bitcoin and Ethereum will become the future of Crypto. But if you have the knowledge, you can invest in other coins that have potential.
I think this depends on the needs. some people need ETH, of course it will be very good for him, especially when the price is rising high. however, never invest only because you want to take advantage of the decline and increase in prices of ETH.