I'm hearing a lot of different opinions on here and at camera shops. One guy warned me that linear polarizers are stronger and less predictable.
Which, to set the record straight, is nonsense.
As mentioned before, the working bit in both types is exactly the same.
The circular contains an extra part, to 'unpolarize' the light again. That happens, of course, after the polarizer has filtered out the polarized light, so has no effect on how it works.
I am buying two polarizers because I don't want to switch filters every time i switch lens. But my question is, if i buy a more expensive slim filter for my wide angle lens and a less expensive but same brand normal filter for my normal lens, will there be very noticeable differences between the shots taken on each lens?
Filters from different brands can vary in quality and effect, due to the polarizing foil they happen to use.
The foil is a plastic, stretched to align the macromolecules in one direction to create something that works as a polarizer, and there are different qualities.
The foil also has to be as near to neural in colour as possible, and again, not all are the same in this respect too.
A cheap brand may (!) be cheap because they use a less good (and thus cheaper) foil.
Or because they use aluminium for the mount.
They could save a buck too by using lesser quality glass. That is: you could think so.
The glass is only in the filter to protect the foil. So just about any clear bit of glass, polished flat, will do. And since the cheapest option is already all that is needed, the cheapest option is used, and there's no opportunity here to make a filter for less money.
Do not be impressed by ad-texts that mention Schott. Schott makes very high quality optical glasses, with a range of strictly controlled parameters. The cover glasses in polarizers do not need fancy glass. So though Schott does indeed make many types of 'fancy' glass, none of that fancy glass is used in polarizers.