What is the best food for a senior cat?

You can buy special 'senior' food for elderly cats. But wet food seems to be better for him. If he throws up food, it may be that if he eats the kibble type, he can't chew it properly, and so has to regurgitate it. Maybe some cheap white fish will appeal to him better, if you have the money to keep up with this kind of food. Cod is perfect.