Percentages are clean on paper. RPE is honest on the floor.
Use percentages when you're fresh, the lift is a competition movement, and you want precise peaking. They're great for testing and for blocks where recovery is controlled.
Use RPE when sleep, stress, or travel is unpredictable. A prescribed "3 reps @ RPE 8" auto-adjusts to the day you actually showed up with.
Most of our programs mix both: percentages for main lifts early in a block, RPE as fatigue climbs. You don't have to pick a religion — pick the tool that keeps you training hard without guessing.