In my opinion, you can invest on btc eth and bnb for long time without notice. Even you should understand when market gone to cheap then you can buy and hold. If you have small assets then i would suggest for eth and bnb even if you have much asset then you can take some with btc. Although there are many good coin for long time so you can check coinmarketcap for more help.
BTC and top altcoins are the best choices for long-term investment and if you are looking for any project, there is no other project which can be more potent than these cryptocurrencies. That is right there are also some projects, which can be also among the best currencies in the future. However, you should make hard research to find one of the potential currencies. There is less risk in investing in top altcoins than in another.