Cockers can't do as much damage as a pit bull or a chow or some other, larger dog, but I believe that Sorcha is right about them being one of the most likely breeds to bite. I think it's specifically American cockers--not English cockers, or the other spaniel breeds. I just know that my experience was that they were adorable as puppies and then turned into snapping beasts as they got older.

Also, I don't know where you live (what part of the country), but they are extremely prone to food and pollen allergies, and consequently often have chronic ear infections that require a lot of care. Probably less of a problem up north but Texas is allergen central and we saw a lot of really miserable cockers with really disgusting ear canals.

I'm not actually saying don't get one, but don't get one from a pet shop. Find a either a rescue that can tell you something about the dog or a breeder with a good reputation where you can meet the parents, ask about health problems, etc. There are good and bad in every breed, and different breeds suit some people better than others.