I have tried to picture out the most stable coin on the market and after enough brain-storm, I discovered that USDT is the most stable coin in the market, it has always be between, $1 and $0.99.
Assessing the stability of x, all comes down to what factor or element we compare x with, in other words, it comes down to the basis of comparison.
Compared to the US dollar, a Stablecoin backed by US dollar like USDT will be by definition the most stable crypto.
Likewise, compared, for example, to the Chinese Yuan, a Stablecoin backed by Yuan will be the most stable crypto.