Check out this site: http://www.dogfoodanalysis.com/
and look under "reviews". The more stars, the better the food.
Personally, I've had good luck feeding Merrick Wilderness Blend and Evangers Pheasant & Brown Rice. Also check out what your local feed stores/pet stores, etc sell before settling on a brand because sometimes a good food can be VERY hard to find, depending on where you live.
Whatever food you choose to buy, make sure you switch the pup over to the new food slowly or the pup could get an upset stomach and/or diarrhea. Mix the old with the new food and gradually decrease the amount of the old food until your pup is getting nothing but the new food -- this process should take about a week. If you notice any gastrointestinal upset, go even more slowly or add in more of the old food.
You can also give the pup nothing but cooked white rice and boiled chicken (no bones, no flavourings) for a few days, then gradually add in the new food over the next week. This works really well for shelter dogs with unknown nutritional pasts and dogs that have medical conditions and/or diarrhea -- it helps stabilize and calm their intestines so they can handle a richer, better food more easily.
Best of luck and we expect pictures of the new pup as soon as you pick her up!
Never make someone a priority in your life when that someone treats you like an option.