If bitcoin price have increased, I can decide to convert some to USD or stable coin. Which one is better? Or is there other alternative which can be comparable with bitcoin in a way it would be independent and having full control characteristic.
I will vote for USD in the bank or cash, not the USDT. It will give you safety and security.
If you are looking to reinvest your money in cryptocurrency and want privacy and hold, USDT is the more convenient option, but the risk of de-pegging is the major concern after the recent UST (TerraUSD) crash.
In my opinion, it is better to invest in GOLD, silver or real estate than deposit the amount in a bank. This way, you will have a liquid asset and a hedge against inflation.