Well, for me this is a difficult one, because both have their pros and cons. But if I have to choose between the two I would go for BUSD. Why? Because Binance is too big to fail. If they want to stay the 'biggest' they have to keep that good reputation. And a lot of their success (BNB, BSC, CZ) depends on it. So if there's any FUD, you can assume that they'll try to back it up with statements and audits as much possible. Tether is much more shady in their doings and lacks transparency. And if you don't trust both, you can always go for USDC. It has some good availability.