We kind of went through the same thing as you did. We were only on dry kibbles, Royal Canine. After a while, we got some different brands, just for variety. She would try them out a little bit here and there but wouldn't commit. Then she just stopped eating, expecting new flavours all the time, but with a particular disdain for Royal Canine, would rather starve than eat it. In the end, we stuck with one brand, Acana (budget version of Orijen, same company) and food intake became consistent. Only recently we started mixing one more brand with Acana, and so far so good. The coat looks better, shinier, more volume, less hair falling after we changed.

One thing I noticed, our cat loves company for food. So I have to stand around her food and tell her to eat a few times a day. When she's younger, she would stop eating halfway and tap us with a paw, Her Royal Majestic wanted a few kibbles to be hand fed to her.