Nutritionally speaking, frozen vegetables are often better then conventional produce because they're picked fresh, and immediately transported to the factory. In addition, most frozen vegetable factories are located close to where they process the crops. Canned and dehydrated vegetables lose many nutrients when they're processed, and often, these vegetables are heavily salted and cooked to preserve them. Recent research has shown that organic produce is superior in nutrition to conventional produce. Surprisingly, the range of nutrient density was significantly higher in the organically produced vegetables, at least twice as nutrient dense, the highest increase being more than a 20-fold difference.
Most organic produce is more expensive then conventional produce.
However, if you consider the increased nutritional value, less stress to the environment and its better flavour, organically produced vegetables are cheaper in the long run than conventional produce. Quite simply, wholistic goodness. It's important to note that the whole is more important than any one of the parts. Many supplements on the market mimic the various ingredients found in vegetables, and there are many vitamin, mineral, antioxidant and phytochemical supplements. This is what really makes vegetables so powerful.