Very true that Argentine Wine is a lot more than "just" Malbec and other big reds. Here is a shortlist of Whites that I suggest folks consider when wanting to venture into something different from Mendoza, Patagonia and Salta.
Mapema Sauvignon Blanc
Encuentro Chardonnay
Aniello Soil Blanc de Noir
Rutini Coleccion Chardonnay
Apartado Gran Corte Blanco
Sylvestra Sauvignon Blanc
Las Perdices Reserva Albarinio
Rutini Coleccion Gewurztraminer
Ciclos Torrontes