The worst way of transferring USDT is by using ERC20 token. Since the Ethereum transaction fees are so high. Most exchanges decided to charge very high withdrawal fees for Ethereum and all the ERC20 tokens.
The most popular cheapest way of transferring or withdrawing USDT from most exchanges is by USDT TRC20, but I doubt your exchange allows withdrawals through the Tron network. But Kucoin does support it.
If independentreserve.com is the exchange you are referring to, check out their fees schedule to know more about the cheapest withdrawal fees using different assets
https://www.independentreserve.com/help/feesXLM seems to be the cheapest asset to withdraw at roughly $0.002
The others are DOGE, EOS, LTC, ETC
Is my logic correct here? What is the cheapest way to transfer cryptocurrencies between exchanges.. Is one coin cheaper to send than all the rest?
Correct.