Ethereum blockchain is best IMHO cause it has largest marketcap as well as still new projects are building up with it. Only because of higher transaction fee, i can't say bsc is better than Ethereum blockchain. Binance Smart Chain just successful to minimize fee, otherwise there are manu things where ethereum is ahead for every matter. Even if bsc get more popular, then fee will also increased. And if binance exchange got hack then bnb might be lost its price badly & bsc might be lost popularity
ETH has the largest cap among all? larger than bitcoin? I am not sure with that but binance smart chain is also growing day by day and I believe that in no time, its marketcap will be the same as eth or maybe more than that.
Devs created a project under the bsc because they want more people to get involved with their project and that can give them more income as well not unlike to eth that only a few people that will get involved on their projects or mostly people that have enough capital and wont mind spending big for the fee. BSC is related to binance but the hackings that can happen in binance exchange are not related on the BSC network. It doesn't stop people from using bsc.