Fruit is an area where some of the popular low-carb diets differ, as some depend more upon glycemic index or glycemic load (South Beach, Zone), while others just look at total carbs (Atkins, Protein Power). Also, some diets (Atkins, South Beach) don't allow fruit at all in the first phase. In general, your best bet fruits are the ones near the top of this list, but do check carb counts. This list is roughly arranged by sugar content according to the USDA database, based on a half-cup serving of fruit.
Good news: the fruits lowest in sugar are some of the highest in nutritional value, including antioxidants and other phytonutrients.
If you are considering buying organic fruits, check out this list of which fruits and vegetables have the most and least pesticides to help you guide your choices.
Quick Tip to Help you Remember Fruits High and Low in Sugar
Fruits Lowest in Sugar