I chose both, although they are almost similar but also very different, the most basic thing is the transaction fee, BNB is cheaper than ETH. Therefore, there are far more BNB users, but on the other hand, ETH users contain whales. The ecosystem is also the same, nothing is different.
the ecosystem is the same but there's definitely some difference there, in bsc there are so many shit coins and newer projects meanwhile in eth even though there higher in fee but the number of quality projects are quite many compared with bsc, even though it can be argued that bsc also have fair share of good quality projects in there, but if i were to choose for investments i'd go with eth first and then bnb since actually both have equal potential as you said.