I've read Martin, Jordan, and Card. Out of all of them, Martin was definately my favorite, with Card bing a close second, followed by Jordan.
I chose Martin because he has a definate talent for keeping the reader emotionally involved in the story and of creating or destroying empathy for a character. He also shows a frim command of the English language in his writing and a degree of historical and mythological intelligence that is very refreshing in his books. Finally, he didn't tell the generic fantasy story (which is not necessarily a bad thing), instead writing a vivid and multifacted world without truly good or evil motives. His characters too, are uniquely human and fallible.