Bret Contreras, often referred to as 'The Glute Guy', has conducted numerous studies on glute activation.
His research suggests that the barbell hip thrust activates the gluteal muscles more than any other exercise.
How to do it:
Sit on the ground with your upper back against a bench, knees bent, and a barbell or weight across your lap.
Raise the barbell by extending your hips, pushing through your feet, and squeezing your glutes at the top.