This depends on your cat. A large, shallow bowl is best to avoid whisker fatigue. Also, it needs to hold enough water to keep your cat hydrated if you are out for the day.
There is no point in buying a huge bowl and thinking that you won’t have to top it up very often because this will not work. Your cat will not touch the water if it has been in the bowl for too long and you will end up having to change it anyway. Also, cats are very good at tipping their water bowl over and you don’t want too much water all over the floor! This is one of the main advantages of raised water bowls.