ETH is definitely the best altcoin on the market. There's no doubt about this. Being the innovator of smart contracts, ETH has enjoyed its position as the second-largest cryptocurrency in market cap for a very long time. It's no wonder why many people trust it more than BNB or any other altcoin on the market. No matter which attractive features other altcoins are able to provide, they can't beat Ethereum because of its large ecosystem of dApps in the crypto/Blockchain space. Besides that, Ethereum is the most decentralized altcoin in existence with a proven track record of development and innovation. BNB is simply the "new kid on the block" that sacrifices security/reliability for performance/convenience. Since BNB is directly tied to Binance exchange's success, the token could die in the future if the company ceases its operations.

I'd say that investing in ETH would be the wisest thing to do right now. Still, people have different tastes and needs. Despite the inherent centralization and limited adoption of BNB, it still has some supporters behind it. With Binance patronizing it every step of the way, BNB could survive on the market for quite some time. It could be used for specific things in the mainstream world. As long as both projects work together to make crypto land a better place, nothing should go wrong. If you know how to play your cards right, you'll be able to take advantage of both coins' success by investing into them for the long term. Just my thoughts