For long-term investments, I recommend that bitcoin or ethereum are the best choices because seeing the market prices of these two digital currencies in recent years have experienced significant market price changes, and if you are afraid of losing a lot of your money then I suggest you invest in only gold because it is very certain to get a profit in the future.
I think BTC and ETH are already too expensive, and the more expensive they are, the higher the transaction fees will be. It is better to look at the potential for coins that are cheaper, and good for the long term such as BNB, LUNA, SOL, or other coins that have good fundamentals.
Well since it was a long term investment, BTC and ETH even though have very expensive transaction fees and cost to invest, still stand above of the rest cryptocurrencies. You looking for something to hold for the long term, not something for daily trade or use, remember?