USDT because prices are stable
All stable coins price are stable.
I don't use stable coins at all however, these are the other popular stable coins in the market's top 100 lately and this list will depend on their ranking as per coinmarketcap.com.
1. Tether (USDT) / Top 4
2. USD Coin (USDC) / Top 24 - made by Coinbase and Circle
3. Paxos Standard (PAX) / Top 30
4. Dai / Top 58
5. Statis Euro (EURS) / Top 92 - backed by Euro