I have a generic no name, well, it probably had a brand name once upon a time, (I have had it since 1981) nylon rain cape. When I sold my bike in '85 I kept it. I used it a lot back in the day. Now I roll with a J & G rain jacket.
If I were to use a cape I think that I would probably go with the J & G cape, based on the quality of their jacket.
I have heard nice things about the waxed cotton capes---I would think that it would weigh more than my nylon one does.
Just my .02