Vicente,
I was in the Secret Service for three years, and have trained in tkd, jkd, bjj, and krav. When I was trained they instructed us in some basic boxing/kickboxing, bjj, judo and krav. Keep in mind, law enforcement entities have a use of force policy that they must adhere to (i.e. they are not necessarily allowed to perform groin kicks to subdue an individual who is actively resisting arrest) so they frequently cannot use the most efficient/debilitating moves.
Agree with many of the above posts, hard sparring is a great eye opener in both standing and ground fighting. I think everyone could benefit from a year or two of bjj since many fights can end up on the ground (keep in mind, some bjj moves lend more to self defense, some to sport; hard to choke a guy with his gi if he doesn't have one and he is punching me in the face). Krav is helpful in that it exposes inexperienced people to effective basic technique and then has them execute it when they are tired/exhausted (fatigue makes cowards of us all).
Ultimately I believe there is no ultimate style/move/technique. Size, strength and skill all come into play. I was once soundly beaten in bjj sparring by a near 400 lb former powerlifter (Im 200 lbs), and no skill I have seen before or since that was allowed in a grappling context was going to help me. I have also had the opportunity to grapple with a highly skilled lady who weighed 110 lbs soaking wet, she was more skilled than I, but not enough to bridge the large size and strength gap.
just my opinions, apologies for the overly long post