from what i hear, the two most effective styles that most people know about are krav maga and aikido. that's what i heard and i believe it because of my gut and not through experience so that's just me. they're completely opposite styles but once learned they're tough to beat.
Nah...i've pretty much crushed the dreams and illusions of both KM and Aikido folks that fight strictly from those paradigms, pretty much any paradigm I've been able to defeat most when I can control the conditions of the fight, which I have gotten pretty good at doing over the years. Hard to explain, but once you understand the secret of how to do it, then you can lay waste to most anyone of any style.
that does not mean these methodologies suck or anything, just that you understand the dynamics of fighitng better.
that and if you spend anytime with Master Ken in Amer-do-te...well then you realize that all other martial arts are Bullshit anyway.