USDT to me still seems a little unstable and considering the law case, personally I try to stay away from it whenever possible.
Fiat is depreciating, yes. Stable coins are fiat pegged coins, yes. But OP was all about which one would come with low fee during swapping. I understood your points, you were never wrong too.
For sure, there are other stable coins representing other blockchains but seems like BNB is still the largest to this day.
You meant unstable coins.