As you'll note in my signature down below i own various lenses. Each has it's own filter size. However, having come over to the light side from Nikon Full-frame all my filters are 77mm in size. So, I have a step up ring from whatever lens I'm using, up to the77mm. So, on my 18-55 which is 58mm, I have a step-up ring from 58-77, etc. etc.
As far a filter brands I've always gravitated to the Singh-Ray brand. They are pricey, but are just amazing. They also offer outstanding service and/or replacement policy, which I put to good use once. Other brands could be Hoya, BW, Tiffen. I have a Hoya Circular Polarizer that is older than dirt and it still works and does an amazing job!
To me, the main thing is to standardize on a size (77mm in my case) then build around that. Many folks, and you'll probably here from many here use the Lee system. To me they are way to over-priced, and almost never in stock.
If you are planning on using any filter with a wide-angle lens, try and get 'thin' filters, and thin step-up rings; doing so will avoid the vignetting where you can see the filter in the four corners of your image. This is an advantage to using the larger, square Lee (and other) system but again, easily preventable.
Whatever you get: GET QUALITY filters from some of the brands I mentioned above. You've spent hundreds and hundreds on Fuji lenses, don't cheap out on polarizers (or any other filter you place in front of your tack sharp lenses). If you take care of them, they will last a long, long time.
Breakthrough's polarizers are some of the finest on the market today IMHO (along with Zeiss and Nikon). I have just received the 62mm that will work directly for 3 different Fuji lenses - I already had the 77mm. I also use step-up rings so I can use multiple lenses with just one polarizer but it is limiting as there is a fat piece out in front of your lens (the step-up ring and polarizer) and the lens cap for that lens will not go on the stepped-up filter. It is not a clean solution, but it works. Preferably, I have 3-4 filters that fit all of my lenses.
Maui got a reaction from Randy Pollock in What polariser should I get for my X-T2?