A good cat will be personable yet independent. It might sit on your lap while you read or watch TV, it might prefer to sleep on a pile of folded laundry, or go outside and chase animals. At the risk of offending dog people (and I love dogs too, and I'm not saying one pet is better than another), I'll make the very general analogy that if dogs are like small children in that they require a lot of care and attention, and give lots of love in return, a cat is like a teenager, obviously dependent on it's owner but prefers some space as well, can be somewhat defiant, with a much more "unique" and often strong personality.
It really depends on the owner's preferences and lifestyle. A mature cat can be left alone much longer than dog owner's I know are comfortable doing so, and believe me they will let you know they missed you when you get back. And of course, just like there are "bad" dogs, there are bad cats, the difference being dogs behavior seems to typically be more trainable, while a "bad" cat will likely prefer to be disassociated for it's life. In the end, they aren't really comparable as pets. If you prefer dogs, you just do, just like if you prefer cats, you just do.