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.
With the way BSC chain works, it's serves as a good alternative when sending tokens.
There are developers who switch to BSC now to lessen the transaction fees and fasten the process, but investment wise
both are really good, especially when taking a long-term hold. There are different perspectives and it's your own understanding
and criteria in choosing what will be the best chain/coin for you.