The ASUS PG279QM has an excellent response time at the max refresh rate of 240Hz. The 'Esports' and 'Normal' OD modes deliver the best overall results, with an extremely fast rise/fall time that delivers extremely clear motion, with almost no noticeable blur behind fast-moving objects. The 'Esports' mode is recommended, as it has slightly less overshoot than the 'Normal' mode. These modes show significant overshoot in all transitions, but it's a very short burst, and the monitor falls back quickly, so it's not noticeable as inverse ghosting. The 'Off' setting has no overshoot, but the average transition time is almost twice as long, resulting in more noticeable blur. Like most monitors, the 'Extreme' setting has much more noticeable overshoot, and unlike the lower settings, this is noticeable as a white trail behind fast-moving objects, so it's not recommended.
Note: Due to the overshoot in the 'Esports' and 'Normal' modes, the PG279QM isn't scoring as well as it should, and the 'Off' mode actually scores higher than what we've included here. Visually, 'Esports' and 'Normal' deliver the best response time experience, and either of those modes are recommended as the best for most people, even though they're scoring a bit worse.