Best is not exactly a simple term - there are a lot of ways something can be best.
Here are two articles from lenstip.com reviewing in detail many polarizing filters.
There's an explanation of the theory behind them as well ( detailed ).
Polarizers are often described as colour neutral, which frankly baffles me for two reasons.
Firstly there are no filters, even ND 0 filters, which are truly colour neutral. The very best ND 0 filters ( maybe Singh-Ray ) are close, but nothing is perfect.
Secondly, the function of a polarizing filter is to block light based on polarization, which is not going to be even across a frame or on every part of a scene. By definition they're going to alter the overall colour balance of a scene if they work.-- hide signature --
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