Just my opinion. "Serious" rugs = Iran Similiar to Champagne vs. sparkling wines. Are there quality sparkling wines made outside of Champagne? Absolutely, but they still are not Champagne. Rugs from Iran are the highest of quality, command the highest resale value and their patterns are copied the world over.
Tribal rugs are very cool, and i actually much enjoy Kazak rugs hand made in Pakistan.... Oushak rugs I believe are hand made in Turkey, not that there is anything wrong with that.