You ask people to tell you which stable coin you should keep your investments in. I guess that you know that this is just another way of investing and you should not do that based on what unknown people over internet advise you do.
Now about stable coins: in order to hold a stable coin you have to really trust the issuer. I don't trust any. USDT is one of the oldest, but its history is full of incidents (real or not) and not always exact 1:1 parity with USD. Most of the others are very new.
So yeah, I guess I just made your indecision worse.
I said I don't trust any. However, you can also check GUSD, maybe that one makes you feel more confident. They've promised regular 3rd party audit and there's a good chance they'll stick to that.
From
https://coincodex.com/article/2328/gemini-launches-gusd-stablecoin/ :
According to the firm, the system will be regularly audited by third parties, and their findings will be released to the public. The token’s smart contract code has been audited by digital security firm Trail of Bits.