Fresh is always best - the organic debate should not distract from the compelling health reasons for eating fresh produce of any kind.
Freshness affects nutrient levels as well as the method by which the food is farmed. Freshness is more related to storage and the time lag before eating than whether a food is produced conventionally or organically. That is a compelling reason for buying local.
You can have wilted spinach that is conventionally-grown and wilted spinach that is organic.
Research clearly shows fresh fruit and vegetables are essential for good health, with health benefits over and above those provided by the vitamins and minerals they contain (this is why taking vitamin and mineral supplements is a poor substitute). If you want more nutrients, eat more fresh produce. Choose carrots rather than fried chips.