BEP20 is cheaper. either sending from a crypto wallet such as trust wallet or from an exchange. If I'm not mistaken TRC20 requires a fee of 1 USDT while BEP20 is only around 0.2 USDT 
I have made USDT withdrawals several times and the fees on each exchange are not much different.
BEP20 has always been cheaper indeed maybe because the centralized nature of the validator but overall it is i think among one of the most consistent when it comes to fee.I have made USDT withdrawals several times and the fees on each exchange are not much different.
i remember when transaction peaked in BSC back then when metaverse was a thing and every little thing requires transaction BSC is the only one that consistently require low fees.
right now it has increased i think due to the fact that there has been something going in blockchain such as inscription and so on. i've seen many contract execution within the blockchain explorer these days with tron i think that has something to do with the fee overall.
My personal experience is that BEP20 is cheaper than TRC20 in the past, yes, maybe TRC20, now TRC20 has changed the gas transaction fees, I think that's why I chose BEP20, it's cheaper. TRC20 is the second choice of network that I chose after BEP20