The Marumi has a bit more of a blue cast, but is the closest match to the white balance with no polarizer on. The Hoya HD does let in about half a stop more light, with a warmer tint with hints of green. The old Nikon linear polarizer lets in slightly more light than the Nikon or the Marumi, but like the Hoya also is a but warmer (not as much as the Hoya) but has more of a greenish tint. White balancing off the same spot in camera raw, the Nikon II and Marumi match the original white balance, while the Hoya and Linear polarizer retaining a slightly warmer, greener tone.  

The reality is that any good polarizer will work well if you are shooting raw on a modern dSLR and can tweek white balance in post processing. The key is good, as the cheaper polarizers are just that, and are often made of plastic. In my experience the Marumi DHG polarizers offer the best bang for the buck, while the more expensive Hoya HD is half a stop faster, but a bit off on the white balance, despite their claim that "HOYA's polarising filters do not affect the overall color balance of a shot."

For whitewater, why I still want to knock down reflections in the shade, the Hoya is my filter of choice for that extra half stop, even though it has the heaviest color cast.