Personally I would sketch, scan it in and then re-colour. There's something about re-colouring from a scanned image that gives off that personal feel to a project. I have a wacom tablet and for 2 years, I've used it 2-3 times which leaves it redundant in my designs.
Again, if money is no object I would personally go for the
Cintiq as you will be working onscreen which outweighs drawing on a tablet from your desk.
You can see the Cintiq in action
here.