To add to your coments about calorie content of foods, in the realm of wet foods, pates tend to have the most calories per ounce, while "extra gravy" foods often have the fewest calories per ounce, since the "gravy" is mostly water.
I'm sure there's some exceptions to this, but I've spent a lot of time creating a spreadsheet comparing foods on a variety of aspects in an effort to find the most affordable foods that work for both of my cats' needs & preferences. If in doubt, the cans should list both kcal/ can and kcal by weight.