You are wondering which one you should buy. Well, there is no single correct answer to these. The answer will depend on what you are looking for in the first place.
Let's try to find out.
Which one to go for if you are looking for the highest nutritional content?
Go for the local one. All the crops, whether grown organically or conventionally, start losing nutrients once harvested. The longer it stays on shelves, the higher is the nutrition lost.
So, if you are looking for nutrition, distance matters the most. Your best bet would be the one locally grown, followed by the one grown conventionally. The imported one will be lowest in nutritional content.
But we have ignored one factor. The imported one is Organic, and it should have higher nutritional content, to begin with, right?
Wrong. Various scientific studies have time and again proved that the nutritional difference between Organic and conventionally grown food is almost nil. You can go through a comprehensive study conducted by Standford Medical School that analyzed 237 published papers to arrive at this conclusion.
Consider this study from Penn State University.
At 10 C, Spinach loses half of its nutritional content in six days. Increase the temperature to 20 C, and it will take only four days to lose half its nutritional content. Consider the average temperatures and storage conditions in India, and you may need to eat almost 3-4 times the regular dose of spinach to get any nutrient at all.
Which one to go for if you are looking for the highest level of antioxidants?
Local, in the above case. Distance matters, and like nutrition, the antioxidant level also falls with time. But what if you can choose between Organically grown local food and conventionally grown local food? In this case, you should go with Organic. Organic food has higher antioxidants than conventionally grown food. Let us understand why?
Conventionally grown food has to fight fewer pests due to the use of strong pesticides. Also, it spends more energy on growing bigger fruits due to use of synthetic nutrients which act faster and are more effective. This means that the plant gets to spend less of its resources in fighting bugs and diseases and hence produces fewer antioxidants. Organically grown food, on the other hand, has to fight a large number of pests and insects. It thus needs to generate enough antioxidants to be able to do so. Hence, food grown Organically has a considerably greater extent of antioxidants.
Which one to go for if you are looking for better taste?
Either locally grown or Organic. If you have both available locally, go for local Organic. This is because the food grown organically grows slowly and in a wholesome fashion. Food grown using inorganic means grows faster and may have a lower level of antioxidants and other taste imparting elements.
Which one to go for if you are looking for the least amount of pesticides?
Neither of the three. Go for something which is certified pesticide-free. Though various studies (including the Standford one cited above) will tell you that food grown Organically has up to 30% fewer pesticide residue than food grown conventionally. But, there is a catch. The numbers they quote are only for synthetic pesticides. These studies do not measure the presence of Organic pesticide residues which can be as dangerous, if not more, as the synthetic pesticides. You can read more about it here.