Stable coin is good product for invest ( long term period ), USDT in any network is the answer but I still use ERC 20. Already have good connection with fiat and liquidity makes a perfect product to use but bad in fees. If stable coin have low fees and use for merchant I think more users will use it. This time work together with many platform ( game, sports, stuff ) will increase fund circulation, do that will make good volatility so users have many option not only trading and investment.