And the winner is . . .

 Mazuri Chinchilla Diet

Photo From AZChins

Why?  Three reasons.  First, it's highly nutritious. This alfalfa based diet has all the vitamins and essential amino acids that chinchillas need. Second, it's highly palatable. Even when mixed with other food, chinchillas seem to pick Mazuri pellets out of their bowls first. And third, it's convenient. This specially formulated diet is ideal for chinchillas of all ages and you don't need to supplement the pellet with others.

Where can I buy it?  Due to increased demand, Mazuri Chinchilla diet may already be available at your local pet store.  If it is not, you can request that it be ordered - let the clerk know that it's made by Purina Mills.  Another option is to order it from online companies, like these two from my preferred vendors list:

http://www.lonestarchinchilla.com/

http://www.geocities.com/forchinatechins/chincessories.htm

Buy in bulk to maximize value and freeze excess food.

How much does it cost?  Cost varies depending on supplier, but most retailers sell it for about $1/lb.

Is there a close 2^nd place finisher?  In my opinion, no.   I personally believe this high-quality product to be in a league of its own, but am willing to compare nutritional information if someone has another recommendation!

***WARNING*** Kaytee brand chinchilla food contains a preservative called ethoxyquin that is suspected to cause cancer in small animals.  Ethyoxyquin is listed as a "pesticide" by the FDA.