They don't do the same thing at all. A hood is there to block all light from outside the displayed field of view with the goal of preventing direct illumination on the optics. This causes internal reflections within the lens and a reduction in perceived contrast due to increased exposure overall while being decoupled from the objects viewed in the scene. The circular polarizers sold for camera equipment cut reflected light at certain angles. This tends to have a greater impact on indirect reflections given the greater variation in the way such things face the camera. They are not the same thing. You should always use a hood as long as it doesn't increase vignetting. Whether to use a polarizer can be more up for debate. It will cut some overall light, so it does require more time per frame or a larger aperture setting.
This seems more like a taste thing to me, but you should be more concerned with your goals for the footage and what you really like about the look rather than the method of adjustment. You don't give much indication of what you're trying to accomplish.
