To me, it has to be the dumbbell split squat for several reasons:
1) The back leg's hip flexor is being statically stretched during the exercise;
2) The glutes (in my case but also in several people I have trained) seem to REALLY fire, especially if you focus on correct pelvic position while doing the bss;
3) The fact that you use dumbbells that you can vertically and perpendicularly hold against the ground makes it so that it loads the glutes really well. With a barbell, there will be some tendency to lean forward and load the quads more in my experience.
The downside to this is that because the foot is placed forward, you don't actually reach hip hyperextension. You will still have a bend at the hips.
So maybe the perfect thing to do would be to combine dumbbell bulgarian split squats with barbell step-ups that end in a complete extension/hip hyperextension where you simulate a jump (end up on the balls of the foot), since with the step-ups you can actually reach the hip hyperextension part and it's also much more specific to one leg jumping. Also, the BSS takes care of the deep, stretched position whereas the step-up takes care of the more specific higher part of the spectrum (where you would finish the extension and take off).
This is one of the reasons I like to do depth jumps and broad jumps/2 leg bounds for two-leg jumpers. The depth jump emphasizes the amortization with little knee bend, whereas in the broad jump or 2-leg bound you will tend to land in a very deep knee bend. If you do them both, then you learn how to control the amortization phase no matter the depth of it, and therefore you can control the entire amortization spectrum. What does that translates into? Better safety and improved performance.
