In the most recent Cook’s Illustrated (Nov/Dec 2009) they did a taste test of different saffrons to see if there is a big difference.
First of all, when buying saffron look for the higher-grade, dark-red threads. These darker hued threads are from the top of the Crocus flower stigma and have more flavor. The lighter threads come from the base and are a lesser grade.
As for taste, Cook’s Illustrated concluded that it doesn’t matter too much which type of high-grade saffron you buy if it is just one of the flavoring ingredients. Most of the saffron in the US is from Spain and they will do just fine. If saffron is the main flavoring, however, you may want to go with a better brand.
Cook’s illustrated recommended two brands: Morton & Bassett – Saffron Threads
the saffron from Penzeys Spices. This last link will also give you a lot of information about saffron, how it is harvested, and the different types.
