A tablet for Mudbox or ZBrush is very helpful.
Onto the main topic. Either one is excellent. But from I have read if you want to model something, like a character, you are far better off modeling in a 3D app like Maya or Max and detail it in ZBrush or MudBox. From what I understand ZBrush does not make very good deformable topology.
As mentioned before it is usually used as a pipeline app. Just part of the tool kit to get things done.
I have figured out what the internet is. You know what they say about an infinite number of monkeys hitting keys at random on an infinite number of typewriters for an infinite amount of time? Well the internet is like that. There is some big cosmic alien running that experiment here in order to find the answer to some big question or to create the greatest piece of literature known to the universe. From what I have seen so far I am sorry to say they are going to be greatly disappointed.