another vote for skeletools, here.
I tried the protec "hip pads", but the pads are thin and not modular (pads non-removable). The sizing is also bad - they only have about 3 sizes and the ones that were closet to my size were still baggy and hanging like a wet diaper. The little amount of protection they give is not worth the other flaws, imo.
RED appear to be more sporadically padded and what they do have are in the wrong places...for me, at least.
skeletools pads are more concentrated, thicker and are removable - so if you only need/want the butt pads, you can remove the rest (that's what I do). The shorts, themselves, are the compression type that fit snug on all areas.
I should warn that if your outerwear pants are "skinny" or even "tailored", they're going to leave little,if no, room for pads. I bought all tailored outerwear before my pads and now wish I would have gone with baggy outerwear...the pads work with tailored, but barely/not ideal