Tougher call than I would have at first thought, but I would on balance go for Steyn; I recognise that Jimmikins has a bit more variety in his ability to swing the ball, Steyn not really having an inswinger worthy of the name, but Steyn bowls at a greater pace and has a really amazxing ability to maintain, even increase, his pace through a long day which Anderson lacks. As regards the ability of Anderson to vary things on a flat deck (or a very slow one) - yes, he has some variety, though he is no Matthew Hoggard in that regard, just someone who has learned a few old pro's tricks. Steyn does not as yet need them - a flat deck at 90+ is still 90+...