Yes, we all have different opinions. But there are a lot of good choices available - one website that has a great break down of the foods and their ingredients is
Dog Food Analysis - Reviews of kibble - I would recommend a 4or 5 star food, some people believe the 6-star foods are too high in protein for the yorkie. You have to remember that site is also someone's opinions
Also, if you have a local pet good store that carries a wide selection of high quality food, go in and talk with the owner or well-educated employees. These people know a lot & hear what customers are saying.
I like Innova, but for grain free I would go with Merrick's Before Grain or the Nature's Variety medallions
If your only choices for buying food at a store are slim, I would recommend Solid Gold at Petco or Blue BUFFALO at Petsmart