Which is better for my cats?

You can buy freeze dried pet treats that are pure meat and will last a really long time. You can either serve them dry or soak them in room temperature water before feeding. Some examples of brands that offer this kind of treat are Halo and Whole Life. I suppose there's nothing wrong with giving them a taste of ham every now and then but I always keep one bag of freeze dried salmon around and it's great because you don't have to worry about it going bad...at least not anytime soon.