Fresh fruits and veggies are of course the best way to go, if possible. But, it should be remembered that every day your fresh fruits and veggies are not being eaten they are losing nutrients. So, if you are one to buy fruits and veggies and let them sit in your fridge for a week and a half until they are barely edible, you should probably find something else that will work for you.
Another good thing to note is that raw fruits and vegetables will hold the highest content of nutrients. Vegetables are water soluble, and when they are boiled in water some of the nutrients are leached out of the vegetables, and into the water. The best way to cook them is to steam them with a small amount of water. If you are going to boil your vegetables, eat them in a soup, and use the water in the soup. This way you're intaking all the nutrients.
Your other options? Frozen, canned, dried? In 1998, the Food & Drug Administration (FDA) confirmed that frozen fruits and vegetables provide the same essential nutrients and health benefits as fresh.resh fruits and vegetables that have been blanched (cooked for a short time in boiling water or steamed) and/or flash frozen within hours of being picked. It should also be remembered that frozen fruits and vegetables are processed at their peak in terms of freshness and nutrition. So I'd say frozen is your next best option. You should avoid vegetables that come with "sauce" included. These usually just add a lot of fat and sodium.
Canned vegetables come in last place. They are usually cooked at high temperatures and lose a lot of nutrients. They are better option than none at all. Canned foods are usually loaded with sodium to aid in their preservation. So rinse them off before eating them.
With all this information, I would suggest you just make sure to have a variety of fruits and veggies from a variety of different sources. This way you'll be well rounded in your nutrients.