I prefer to hold DAI because it's decentralized and can't be frozen.

USDT is centralized, can be frozen and not 100% backed with real USD fiat, so it will be more dangerous to hold rather than USD. Even though it's on top 3 market cap and has many holders, but both of them aren't guarantees to say it's safe.

Read more here [UPDATED] PSA: Most Stablecoins Can Be Frozen, Even in Your Own Wallets