I made it to Green belt in Goju Ryu Karate while in college. Black Belt in Tae Kwon Do though the instructor borrowed grappling techniques from other styles. Worked with my son's wrestling team doing freestyle. Also the mish-mash of techniques the Army calls combatives. There are other bits and pieces of styles that have been picked up here and there.

As much as I enjoyed TKD, in my opinion it has its limitations. The lack of grappling/ground fighting is the biggest. I've seen few fights that didn't end up on the ground. I also didn't like the emphasis on high kicks. I'm a firm believer in attacking the base.

Overall, I'd have to say the most effective style/technique is the one that works for you in a given situation. I try not to be tied to any one thing.

YMOS,
Tony