Imo, the most regulatory compliant is Circle's USDC. They have been very open to regulations and have even opened their books to audit and are a publicly tradable company since their CRCL stock is listed and tradeable on the Nasdaq. It's also safe to say that USDC is the most integrated stablecoin after USDT as you'll find it on CEXs, DeFi protocols and basically everywhere else. So it's just like USDT only that it's much more complaint. When the clarity act is approved and set in motion, USDC will be one pf the biggest beneficiaries.
I've seen more and more USDC adoption lately on DEX. Every projects that needs pre-deposit and allow staking always use USDC as the primary stablecoin to accept. USDT is showing decline in projects like these.
This imply that even projects that have done their due diligence consider the USDC to be a safer option than USDT. However since OP want alternative other than USDT or USDC, it should always be DAI or USDS because it is basically a wrapped USDC without freezing function.
There are many other stablecoin that are pure t-bill backed with monthly audit and routine audit report publishing but I won't dare to recommend because liquidity isn't that high.
