in my opinion the best is usdc, for the reason he already has a lot of exchange and also the fee is very low because it is still in ethereum network and also the decrease is not too severe like tether.
i believe there are no stable coin in this crypto market because the amount of token are too many but only very few has a high value, these low cryptos can easily be manipulated by whales, unless we invest in top altcoins, it is still safer than other cryptos, none of any crypto is stable when this crypto is too small when compared to the world market.