When comparing protein and fat contents of various foods, you need to do it on a dry matter basis (what it would be if the water was removed). Those are the statistics I supplied for the various foods. Stella and Chewy had a gross labeling error on their website for moisture content of their freeze dried chicken patties, but it's correct on their bags. If a dog is prone to kidney problems or bladder stones, super high protein content is not a good thing to be feeding. Ditto high fat content and pancreatic issues. With calcium and phosphorus, it's not only the amounts, it's also the ratios that are important. Home made foods and raw diets are often way out of whack. AAFCO sets guidelines on the amounts of phosphorus and calcium, as well as the calcium to phosphorus ratio, so it's less of a problem with commercial foods that follow AAFCO guidelines. See
http://www.aafco.org/Portals/0/SiteC...t_Profiles.pdf for their 2014 guidelines.
I'd place Farmina and Wellness on about the same level: nutritionists on staff, feeding trials, good quality control. My only issue is that the protein content is a little high for both of them, but then again, I'm feeding Wellness to Bella and she seems to be doing okay.
Acana looks more like the kind of food that I would be more comfortable feeding to Bella, but since she's doing well on her current food, I'm not planning to switch. I'm glad that you're having a good experience with Acana. I'll keep that in mind if I have to change her food in the future.
I do remember some kind of lawsuit going on between Blue Buffalo and Purina because Purina had Blue Buffalo food tested, and Blue Buffalo contained different ingredients than what was listed on the bag. Something to keep in mind. Purina makes some good foods in their higher quality lines, and I believe that they make some prescription foods as well, but I would not feed their regular dog chow line.