Most definitely another vote for wet (or raw!). However, I personally curse the day that some bright spark invented complementary wet cat food!
Cats are not naturally good drinkers, which goes back to the time when they would have satisfied most of their moisture needs from the prey that they catch - meat contains a lot of water but they also drink the blood of their prey. So, for example, raw food contains about 70-80% of water, and wet food contains about that too. Now compare this to the 7-10% of moisture content of dry food.
Indeed, studies have shown that cats who are fed a diet consisting of wet food that contains about 70-80% of moisture don't tend (and don't need to either) to take in any more water from external sources. Also, cats who previously were fed dry food and were drinking a lot stopped drinking from external sources when fed a food high in moisture content.
Ok, so people who feed dry say that their cats drink more and are encouraged to drink more using water fountains etc. Fair dos one might think. However, studies have also shown that although cats drink a lot more than wet-fed cats, they still don't take in as much moisture as cats take in from their wet food, which leads to more concentrated urine, which CAN lead to urinary and other issues.
For example,
Water Intake/Urine Volume in Cats Fed Dry or Wet Food
........................Wet Food (mL/day).......Dry Food (mL/day)
Water (in food).............246............................6
Water (in addition to food)32..........................221
Total Water Intake.........278..........................227
Fecal Water ..................27............................44
Urine .........................166...................... ......79
http://www.hillspet.com/media/_refac...actDisease.pdfHowever, don't get me started on the "dry food improves dental hygiene argument" that vets over here are still promoting too!