Giving advice on feeding your pet can be quite difficult with so many options available in pet foods these days. For the most part, many of the diets out there are well balanced and your cat will likely receive the proper nutrition with a majority of the diets that they eat. I would like to give a few suggestions though when choosing a diet for your cat.
First, a little background on cat's nutritional needs. Unlike dogs that are omnivores, cats are strict carnivores. In the wild, they would typically eat small mammals like rabbits and mice, so their protein and fat requirements are high while their need for carbohydrates is low. When you break down a typical mouse they are around 55% protein, 38% fat, 2% carbohydrates, and the remainder a mixture of minerals and vitamins (with a moisture level of around 65%). Looking at many commercial diets you may see that they can have carbohydrate loads upwards of 20-30% (which is typically very high for cats) and the dry diets have moisture levels of around 10% (which is very low for cats).
So then, what do I suggest that a cat eat. First, feeding an all wet food diet or mostly wet food diet is helpful. This helps a lot with hydration, which is important (especially in male cats). Many cats can get urinary issues when they are chronically dehydrated and keeping them on a wet diet helps prevent this. Also, a diet low in carbohydrates (hopefully less than 15%) with a protein level higher than 30% would be ideal. You can check out this table to see where your pet food stands. Making sure that the protein sources are from a meat source and not plant source is important as well.
The other issue is feeding the correct amount of food for your cat. Most cats only need between 150-250 calories per day of food, which typically comes to around one 6 oz can of food or 1/3-1/2 cup dry food per day. More active cats will need more food while less active ones need less. A typical cat is ideally around 12 pounds.
Another good resource for feeding your cat can be found here.