It depends on your skin and your needs. Differin is more user friendly and better for sensitive skin. When I used it, my blackheads cleared but I still got a few whiteheads. Retin a will do a better job drying your skin but if you use too much, or to often you might suffer the side effects. Irritated dry scaling skin, and the increased sensitivity to sunburn. Retin a is far less expensive than differin if you're paying out of pocket.
I can't speak for spironolactone.
You might consider adding benzoyl peroxide to your routine.
good luck