I can only speak from the experiences I have had and currently have. We have two dogs, two cats, two hamsters and now two hermit crabs. I would say that the dogs are definitely the most "high maintenance", meaning taking the most of my time, but the easiest to please. Of all I have experienced, it is actually the hamsters that I worry the most over, simply because they seem to be the most unhappy...always trying to escape . It is sort of sad, although Helen and I take time each day to play with them and give them time to "run" around out of their cages. Cats are definitely the easiest in my opinion! Even though my Butter gives me a daily "test"!