Both are quality carbs, but timing and goals matter. Sweet potatoes have a lower glycemic index and more fiber, creating a steadier blood sugar rise. That makes them ideal for sustained energy at lunch or for longer workdays.
White rice digests faster and creates a quicker insulin response. This is useful post-workout when you want to replenish glycogen rapidly and drive nutrients into muscle.
If your goal is steady energy and appetite control, choose sweet potatoes. If your goal is recovery and performance right after training, choose white rice.