Coins such as Ethereum and BNB are must have if you have interest in investing in altcoins. I believe they're now the two most important blockchain in the ecosystem as such more decentralized application will be built on both blockchain and their native tokens stand to benefits. BNB is a force in the exchange business and now they'll be getting more shares of the Market as a competition has been taken out of the conversation while Ethereum blockchain will become more effective since they have upgraded from PoW to PoS.
I think any investor hoping to benefits from all areas of the market needs this two coins and Bitcoin. For now nobody knows the new trend to research on and invest so it's best you invest in the coins that have already proven themselves while we wait on the new trends to get in early and make life changing gains.