When looking at commercial rabbit food's you first want to make sure it isn't filled with unnecessary and actually harmful ingredients. Avoid those "gourmet" pellets with seeds, nuts, and dried fruits. They do more harm than good. A nice plain pellet, while appearing bland, is much healthier. Of course our bunny friends like variety in their diet just as much as we do, so that's why providing different types of fresh veggies is recommended, they also provide extra vitamins and minerals.
Look for the nutritional content on the bag. What you will want to see is;
First ingredient should be;
Timothy for a rabbit 8 months and older.
Alfalfa for a rabbit under the age of 8 months.
Fiber: 18% minimum
Fat: 2.5% or less
Protein: 16% or less
Calcium: 1% or less
Kept in mind this for an indoor companion rabbit.