If you want to drop fat quickly, cardio is the way to go. However, if you want to keep fat off in the long run, I'd say lifting weights with high intensity would be the best bet. Running has no effect on your resting metabolic rate because it doesn't provide any lean body mass growth. As a result, once you stop running twice a day, as I suppose you will eventually, and continue to eat the same, you will gain your weight back. Building muscle allows you to increase your RMR, thereby allowing you to either eat more without consequence or lose weight eating more than you're used to. In other words, lift weights (with intensity) instead.
www.crossfit.com is a good example of something like this.