It depends on you, but if what is more secured for me, I will choose to use usd or fiat to stop my cryptocurrencies from losing value in a bearish market, though I have been using tether for trading in some cases. If you choose it to stop your cryptocurrency from losing value and use exchange or online wallets to store it then you have to rely on exchanges the security of your coins which is of course very risky especially if you have plans to have your funds in tether for a long time. But of course you can secure it by your own. So for me, for short term tether and fiat if you don't actively trading cryptocurrencies or waiting for good timing to enter the market again.