Merrick seems to be better balanced than Go and Now. Protein is great, but is not the only thing to be concerned about. Fibre content, for instance, is only 1.5% in the Go! Fit and Free, but is 5% in the Merrick Adult Chicken. Merrick uses only ingredients that are local to them (Texas). They don't out-source any of their products, nor do they make recipes for other companies. Go! uses North American ingredients, but minerals may be foreign. Merrick also breaks their line into life stages. Both foods seem to be highly palatable. Go!'s kibbles are quite tiny, which may pose a problem for some adult cats. Conversely, Merrick's kitten kibbles could be smaller. Go!'s bags seal better than Merrick's.
I don't trust Merrick as they have had a few recalls. I feed go fit and free to my 6.5 year old cat and he is doing very well on it. He's only 6.5 years so maybe it is too soon to tell. But he loves it. His coat is shiny and super sleek, and he is as active as he was when he was a kitten. I also like that I don't have to feed as much. He doesn't have a problem with the small kibbles but that doesn't mean other cats won't. I think Petcurean is coming out with new formulas. If your cat is less active I would go with the Now.
Every company, if its around long enough, will have recalls. It happens. My father worked in a factory for fifty years. The factory has been there for one hundred and eleven years. It doesn't matter, he says, how careful you are, how strict you are, things will happen. Machines will fail. Humans will err. These days, mistakes are less and less frequent, thank goodness.
I fed a cat food many years ago that had been around close to twenty years, at that point. It was recalled because the packaging was misprinted.
I'm not trying to say that these things don't matter, because they do. Its just not the end of the world.