Each coin has different advantages.
ETH is a long-established platform currency and is trusted by many investors, while BNB is backed by the world's largest exchange.
I think in 2021 these two coins are still competing with each other and no one has outperformed yet.
I agree, both blockchains are backed up by huge projects and a big capital, And both are good for the tokens propose. That's why it's hard to say one of them is better than the other one.
I prefer ETH because they was the first ones with the idea, I feel like BNB is just a copy and not an original idea, but isn't a bad copy at all, they come with the lowest fees and that was a nice move.