Global top three by familiarity
Cabernet Sauvignon, Pinot Noir, and Shiraz or Syrah are widely recognized and easy benchmarks for red wine drinkers.
Red Wine Guide
What are the top 3 red wines?
If you mean the most famous global red wine grapes, Cabernet Sauvignon, Pinot Noir, and Shiraz or Syrah are often a practical top three. Pinotage belongs in the conversation when the focus is South African red wine.
Where Pinotage fits
Pinotage is not as globally common as those grapes, but it is the defining South African red grape and worth trying for smoky, savory, dark-fruited styles.