1 cup cooked brown rice: http://nutritiondata.self.com/facts/...d-pasta/5707/2
baked, flesh + skin, med potato: http://nutritiondata.self.com/facts/...roducts/2770/2
whole wheat spaghetti: http://nutritiondata.self.com/facts/...d-pasta/5784/2
they offer similar nutrition.
potatoes give more complete balance of aminos, will make u feel much fuller (i.e. eat less), and give a bit more percents of vitamin (especially vit C). also has less than 1 gram of fat, and low calories (161)
brown rice has 2 grams of fat per serving, packs 5 grams of protein, has 216 calories, offers significant selenium
whole wheat pasta offers the most protein at 7 grams, is low cal (174 g) and low fat (1 g), also significant source of manganese and selenium
if you are trying to decide between which ones to eat more often it kind of depends on you and your nutritional requirements. i agree with everyone else that it is best to eat a variety of all 3, however if for whatever reason you are looking for the best choice out of the 3 i would go with potatoes because they give a bit more in the areas of vitamins and minerals and also help you to feel more full.