Besides ETH and BNB, I think you can choose QTUM as your long term investment. They continue to develop the project, and also currently QTUM's price is cheap, so you can buy now and then hold it until 1-2 years later, see what you will get. I personally still hold some QTUM ss my long term investment.
QTUM is a very underrated cryptocurrency these days. It's old, but still alive and running after all these years. Interestingly enough, QTUM is a smart contract platform like EOS, ETH, ADA, and TRON. But its popularity is down the drain. I guess that most people are focused on the big players on the market, than anything else. The rise of "De-Fi" and stablecoins' popularity has placed ETH and some other smart contract platforms in the headlines. QTUM is a hidden gem waiting to blossom someday with its unique features not found on its competitors. Same applies to NEO (formerly known as Antshares) and DASH. Prices seem to be getting lower over time for these coins. Holding "old" coins for a long time might pose to be a huge risk for your investment.
Nonetheless, there are many "old" coins on the market that have been performing well after all these years. Dogecoin is a good example of this, being a cryptocurrency actively traded across several crypto exchanges. Despite being abandoned in development and innovation, it has retained trading activity, making your investment last a lifetime. Litecoin, DASH, and Monero have been doing well too (although most other coins have experienced higher gains in price). If they're able to maintain mainstream adoption, they'll be able to survive for many generations. I'm currently "hodling" DASH, LTC, and some XMR, hoping they'll remain actively traded in the future. They serve as an alternative to a retirement account, if prices remain the same or higher than what I've invested initially. One thing for sure, is that investing in "old" coins brings many more risks than it's the case with newer ones on the market. I'd advise anyone to invest more on new coins, while allocating a small percentage of the investment into "old" coins to reduce risks as much as possible. Just my thoughts