I'd probably be a W is they still made them. (Unfortunately, Mac had mostly switched to the NW/NC by the time it made it to my market.) Prescriptives Red (R) or Blue/Red (B/R) shades have some serious, though still natural looking pink undertones, comparable to Mac's W. I'm guessing NW20 is too yellow/peach for you? I have that probably, too. I have really pink/blue undertones and even the NWs look yellow on my skin. Actually, I play them down with a straight N shade (only in studiofix, though. boo).
Sorry to veer OT. On the drugstore end, L'Oreal makes some pinky/beige shades in true match. Someone at MUA made a foundation equivalencies chart. A nice addition would have been some long-discontinued shades.