If you asked 10 different people which dog food they recommended, you would probably get 10 different answers. There are so many choices, and a lot of good foods. This website has analysis of hundreds of different dog foods.
Dog Food Analysis - Reviews of kibble
Anything in the 5 star category would be a good choice for your yorkie. The 6 star foods are very high in protein. (some vets don't recommend feeding yorkies above 25% protein).
Some 5 star foods that I recommend are Innova, Wellness and Timberwolf Organics. (My fussy eaters were crazy for Timberwolf).