The large WCW microfibres are excellent, as are the Unger ones, and at 4 quid a pop they are hardly expensive considering how long they last you.
Years back you could get several different grades of scrim, but now they all seem much of a muchness and are not of the same weight they were years ago...and they are not half as good as microfibre cloths.
Scrim is fine, but micro is most definitely the way to go...
Ian