Hydroponics is cleaner than soil and the plants grow quicker. Some prefer organics because they believe the bud cures better and is more flavorful. If you want a high THC content, you have to start off with a strain that has that characteristic, regardless of the method or medium used.
Hydroponics produce more volume quicker, but the taste, flavor, and potency of soil and organic grows cannot be surpassed. As Serapis has stated, the potency is largely pre-determined by genetics and the final results lie in the skilled hands of the grower.