i would X4 the Purdy or Hamilton recommendation but a mate of mine had some synthetic b+q (i think) and they were very smooth with emulsion. nicer to cut in with than my hamiltons.
whatever you buy though, it's going to be true that cheap brushes, whatever label they have on them, will probably be crap although not everyone can tell the difference....
whatever you buy though, it's going to be true that cheap brushes, whatever label they have on them, will probably be crap although not everyone can tell the difference....