heres a pdf of most of the canned cat foods available in the market. compare the Protein, Fats and Calories also the Phosphorus of each brand.
You will see that even some of the cheaper brands are nearly as good(sometimes better) than the more expensive ones. Some of the better brands are very high in Fats.
However Grain Free choices are always tops. Beware of anything with gravy or sauces as these are high in carbs the ingredient in thickeners...thus lead to weight gain.
http://catinfo.org/docs/FoodChartPublic9-22-12.pdf