Hmm tough one I have done it all myself, but the best i would have to say would be Krav Maga that is some pretty tough ****, I also enjoy Shaolin Northern and Southern style using all 5 animal technique but i am especially good with the Snake, I took Aikido which was also pretty good and i was given private lessons of Muay Thai kickboxing and Nin-Jit-Su. The guy who taught me Nin-Jit-Su was really cool, he gave me a look at something that recorded his genealogy back to like 1200 A.D. or something around there, and it turns out some of his ancestors really were Ninjas(NOTE: ninjas weren't very honorable, they were thieves and *assassins and murderers) but still they knew how to fight, their philosophy was BASICALLY anything goes as long as you emerge victorius. I took some Bo-Jit-Su or something like that for about 2 weeks, it was tough unfortunately the guy who taught it to me got a job offer to another state so he left which sucked. One of the Funnest and most advanced, dangerous, and extreme Martial Arts i have ever taken was White Dragon Kenpo(THAT WAS SOME EXTREME STUFF) when i was at those classes i would usually come home bloody and usually once a week i would get knocked out(Yes this is the version of Kenpo that Ed Parker perfected). I also was privately taught Shin Yi(it is what Yulaw used in the movie The One) that is some pretty tought stuff, the basic theory of it is to move in a straight line(fastest distance between two points) and just rip through anything that gets in your way, it is really hard to learn though, but if you ever get attacked by numerous people it will help you considerably.
Incase you are wondering, the art that the good Jet-Li(Gabe) used in The One was called Bagwa, it is passive and not offensive like Shin Yi, I myself have never been taught it but i have seen it down upclose.