I personally can't hold altcoins for a long time, maybe for a recommendation I think ETH is worth holding long-term.
in this market no one knows, how the future will work, it could be that new altcoins can get the top position in the market.
You''re right that altcoins is not really suitable for long-term holding. However, ETH is an exception. Holding ETH is always a good choice, especially for the current market condition. ETH is always a good investment for me. Since I started trading and investing in this market, I always keep some ETH in my wallets. Right now, I'm holding BTC and mostly ETH in my wallet since I realized ETH can gain more and more.