Bep20 is cheaper now because trc20 now charging more fee and it is remain no cheaper network. 2-3 years later TRC20 was most cheapest network and sending fee was just one trx(0.02$) but I checked one year ago by sending usdt to other addresses and trc network charged 2$ per transaction which is higher than many network.

BSC network fee is just 0.05$-0.1$ which is very low as compared to TRC. If you use Matic then it is cheaper than both.