by how much is been used in many tokens, BNB must be the closest competitor of ETH. its even more friendly and its fees are cheaper also. they use say ETH killers when there are projects related to smart contracts like SOL and ADA but they are not just that widely used by many developers. there are more projects even before BNB and SOL but none of them came close to ETH killer.
Solana is also a big competitor for Ethereum because it is very fast and very cheap. In 2023, Solana received a large amount of capital from investment funds and made an impressive comeback after the collapse of FTX. Although Solana's ecosystem is developing thanks to memecoins and its network is still unstable, it is really competing with Ethereum in terms of popularity, users and Dapps. I really like the idea of Sagaphone from the Solana team