I've used one of the English Selvyt polishing cloths from Frei & Borel for about 15 yrs now. The perfect polishing cloth. I throw it in the wash about once a year/as needed.
This is the 10"x10", part # FB 313.
The Selvyt is certainly not necessary. I'm sure any 100% cotton cloth or maybe even the microfiber cloths designed for auto detailing would do the trick. Now that I think about it, Allen Edmonds sells a flannel cotton polishing cloth that would work well.