These two coin are great potential coin and also top cryptocurrency in the globe today. Everyone have reasons for choosing among the two which to have or either both, personally I would prefer BNB it economical in terms of all usages this mostly include for making of payment, building a project via tapping on it network, as well as sending out transaction with less expenses. It can used by everyone irrespective of fee but ETH can not be easily be used for transaction without owning enough quantity for fill out the gas fee leaving a threat amongst it's users.
Why don't you choose both BNB and ETH?
It is a good investment strategy to diversify your portfolio. Rather than having only BNB or ETH in your portfolio, it is better if you own both of them.
It is even better if you also have Bitcoin in your portfolio too. I mean Bitcoin, Ethereum and BNB are most important cryptocurrencies you should have in your portfolio.
For others, you can choose FTT from FTX exchange, KCS from Kucoin exchanges because so far they are good exchanges and they have been tested enough by the market. In next bull run, their exchange tokens will grow well that is good for your portfolio.