Of course it is BNB. Firstly, both BNB and Ethereum support smart contracts, and when Ethereum started seeming impossible with its fees, it was BNB that took over. Also, transaction speed and cost is another reason why BNB is Ethereum’s biggest competitor. Lastly, Binance has gained huge attention in the past years. It has grown so much and this equally has increased the strength of the BNB token.
BSC is a copy-paste of the Ethereum blockchain and yes it is a big competitor of it. BNB is required to use the Binance smart chain which is why there is a demand for BNB. Another competitor that has emerged recently in the market is the Solana blockchain. A lot of meme coins are now part of the Solana ecosystem which is the reason why everyone is now interested in it. Another benefit of Solana is its cheap fee like Binance smart chain has which is why these two are good competitors of Ethereum now.