When you talk about trusting a coin, you have to look at different achievements of the project working with the token or coin, the background and level attained. To me, Ethereum is a base token and can't be compared to BNB, unless there's better and strong competition from BNB. I go with Ethereum.
I also believe that you can not put these two coins in the same row, since they have completely different functions. BNB is the coin that created exchange Binance and the value of which is very closely related to the functioning of this exchange. And Ethereum is the basis for most cryptocurrency projects.
Each coin will perform different tasks based on their development strategy, but based on their requirement companies will use, during the ICO, ETH is the most convenient one for investing, but once ICO is completely focusing on the negative way, then IEO came into existence now every exchange are using their own base token which the demand for ETH kept decreasing.
both of which are potential altcoins, where ICO had triumphed in its time and once ICO was dim, IEO was the first choice. but both have a large community and I think both are worth investing. and this I do to invest in the two altcoins, in addition to bitcoin, as long as bitcoin goes down, then both altcoins also follow down