I'd say Pierre Thomas but it's close. Both guys play in explosive offenses but I expect Thomas to get more work around the goal line. Neither guy will get 20 carries a game though. Thomas will have more scoring chances, so I go with him.
White and Austin should both have great seasons. Cowboys are lining Austin up in the slot to make sure he doesn't get double teamed as much while White and the Falcons are going to be more up-tempo this season with no-huddle sets. Either guy should be solid. If I had to choose, I'd go with Miles Austin.