The two cats I have right now have only ever eaten 9Lives. The cat I had before this, I bought Purina One for because he was a long haired and slightly overweight baby who had troubles with hairballs on a regular basis. I have been thinking of changing brands because of Mouth's asthma, but since most dry foods have the same main ingredients, I am not sure it will be helpful. Do you think the more expensive brands like Blue and Science Diet are worth it?