After the horror of the melamine related 2007 Menu Pet Food Recall (and the never officially recognized 4000+ sacred pets who died) I did tons of research, made lots of phone calls and wrote letters. Look for named meats (not by products, corn, or fillers) as the first 2 or more ingredients. As of 2019, be aware of potential for DCM (heart disease) related grain free diets. There are many good brands out there. Here are a few:
Nutro Ultra Toy Breed
Wellness Toy Breed Line
Solid Gold Mighty Mini has the smallest kibble - great for tiny teeth or toothless old pups :) .
Castor and Pollack Organix Small Breed
Avoderm Chicken and Rice Small Breed
Missing Link: This may help coat, reduce itching/allergies, tear stains and more.
1/8 tsp is all you need for tinys :)