Glenn McGrath for Australia. I've seen too much of wayward Johnson while hoping instead for the Johnson who demolished South Africa and England in a couple of tests in 2009. It's mainly due to Johnson that I'd take the Metronome over Warne.
Shaun Pollock for South Africa. Pollock-Steyn-Morkel could have been a devastating trio, and would have ended South Africa's search for their third seamer. He would have also strengthened their lower order batting, which is possibly the weakest it has been since readmission. A pity they didn't play much together despite being around for 4 years since 2004.