They are all crap stablecoin blockchains, but if you need to engage with them, then you are stuck using those that are the most popular among them. I have never used or heard anyone use USDT on Polygon or the BSC network. It's mostly the asset on Tron followed by the token on Ethereum. And the fees are cheaper on Tron. Even the source you linked to shows it. I never had any staked TRX, and the fees I needed to pay for USDT transactions were either 13 or 26 TRX. At the time I last used it, it was between $0.70 and $1.40/1.50. It surely costs more now with all cryptos up in value. 

But yeah, if you have some staked TRX, you can use the energy it produces and convert it into fees when engaging with smart contracts, which token transactions are.