Instead of comparing which one is the best, we better think about which one is more efficient for us to trade, and of course if we look at the fees, of course it would be better to trade on BSC because on the BSC platform the fees given tend to be cheap because they use cheap BNB but not all tokens in BSC also have low fees. BNB is still much different from Ethereum, for me it is more feasible to trade on the BSC platform for now, but if the et fees are low, I might use both platforms.
Now things are a bit different because we have BSC growing so big, however that wasn't the case just few months ago, back in early 2021 or a bit before that BSC was empty land and that is the reason people still preferred paying 40 bucks on ethereum gas fee over investing into anything in BSC because there wasn't anything to invest. So when one place have 500 projects in it and other has maybe 10 at best, you know that you are willing to lose money on each move, you limit your moves but you still took those.
However these days it is getting a bit different, ETH has lower gas fee once again, not as cheap as BSC still but getting there, and meanwhile BSC has a ton of projects, maybe even more projects than ETH at this point. So it is a bit of a confusion, it is not simple and it will never be simple but it is still a very fun thing to compare and it is never a clear answer for many people.