Orange with pulp is the best way to drink prepared orange juice.  The fiber of the pulp contains cancer preventing flavonoids and cholesterol reducing fiber.

Oranges, Citrus sp. Family Rutaceae, with their vitamin C content are best known for preventing scurvy.  They are a mild laxative and diuretic.   A tonic herb, like grapefruit, oranges are high in calcium and potassium.  Flavonoid and pectin content in oranges provides cancer protection with their antioxidant qualities.

Orange flowers are used in infusion as an antispasmodic and soporific.

Also see lemon and limes.
Grapefruit, Citrus paradisi Macfad., Rutaceae with vitamin C, potassium and folic acid.  It is stimulating to the appetite, considered a tonic, with antiseptic qualities.

Pectin from grapefruit lowers cholesterol absorption and may help reverse atherosclerosis.  Pectin makes up the cell walls of the grapefruit so it is necessary, like in orange juice, to eat the pulp or the whole orange or grapefruit.

One study in Sweden suggests that grapefruit is anti-cancer particularly to pancreatic cancer.  

Grapefruit and grapefruit juice may enhance the effect of drugs such as cyclosporine, antihistamines, estrogens, quinidine, benzodiazepines, dihydropyridine.

Dihydropyridine calcium channel blockers are enhanced when taken concurrently with grapefruit juice, enhancing the hypotensive effect (lowers blood pressure).

Try grilling grapefruit with oily foods: duck, goose, fish.
Bergamont orange, Citrus bergamia (C. aurantium var. bergamia) used as an antispasmodic and digestive, the flowers are used to flavor desserts, sauces, pastires.  Orange blossom water from this species is also used to calm colicky children.  Oil from the ripe peel is used as a douche for fungal infections, vaginitis.  Aromatic oil considered soporific.

Clementines, Madarin orange and tangerines are used as food to treat gastritis, bronchial congestion, liver and gall bladder complaints as well as indigestion, vomiting and coughs.