To answer your question in an unbiased manner, there really is little difference in nutritional value between organic foods and conventional foods. In fact, the slight difference there is will usually fall in favor of conventional foods because synthetic products help them grow stronger (more fiber, etc).
However, people do not eat organic foods because they are more nutritious, they eat them because they do no contain other chemicals and (let's face it, poisons) that are used in conventional foods. Because farmers do not have the aids of special fertilizers, sprays etc to make their 'watermelons larger' and therefore more profitable, they need to raise their prices. Further, they do not spray to get rid of insects and other foragers, so crop loss due these factors is very real.
Ultimately, as the person above suggested, if you eat peels and skins (the most nutritious part of most fruits and vegetables) then buy organic for sure. If not, I recommend starting by substituting some of your fruits and vegetables over time. I eat about 70% organic.
GL!