Fat, protein, carbohydrates, water and taurine - they are elements to consider in selecting a cat food. Note the serving size when considering cost.
The benefit of wet food is that it contains more water and is a closer representation of what a cat would eat in the wild. It digests more easily thereby resulting in less but softer fecal matter and may be more palatable.
The benefits of dry are that is does not spoil when sitting out, is less smelly and results in more, but firmer fecal matter. Your cat will have to eat more to get the protein it needs (because some foods contain a fair amount of filler and carbohydrates) and long term this could create a weight problem if you are not buying a premium dry product. Dry food might have some dental benefits from the “crunch” aspect but should not be considered a replacement for brushing your cat’s teeth. Provide lots of access to water.
If you put anything wet - water, milk, wet food - on dry food, bacteria can grow on it, so keep separate bowls for your types of food and water.
Check with your vet. Perhaps a balance of wet and dry depending on your lifestyle and your ability to feed your pet throughout the day. Any changes should be made gradually.
An overweight cat is more at risk for diabetes.