I present the details for my choice based on what I read:
1) Grain-free foods have been linked to heart diseases through studies by the American Kennel Club (AKC.org). It's still early, but it's an indication. This specific one has few grains, which I want.
2) Taurine helps strengthen the heart in dogs (again, mentioned by the American Kennel Club). This specific one has added taurine 1000mg/100g.
3) Lamb is tasty and nutritious, and this specific one doesn't smell bad at all.
4) It has 35% protein, and for a golden retriever, although not small-sized, I don't think it will have any problem. Besides, with plenty of water, it will be fine.
5) Farmina has fantastic reviews from hundreds of customers.
6) I feed it in 3 portions with a little water soaked in the bowl, and I have no complaints about fur or feces (golden retriever). The kibble size is relatively small, like a large lentil.
7) Very good price as I consider it on par with Royal Canin. Not as expensive as Orijen, but due to the lack of grains in Orijen, I don't know if I will ever go there, even if they become cheaper