Awta plus the Kallis Factor. No way is the English attack "vastly superior" to SA.
Steyn and Anderson have been bowling to pretty much the same standard for 2 years now. Steyn's number 1 but the difference these days is minimal.
Morkel's bowled well, as has Tremlett, they're pretty equal. Morkel has been doing it longer, which gives him a slight edge.
I'll take Broad or Bresnan before whoever South Africa pick as their 3rd seamer. The fact we have no idea who that is tells you how well they've replaced Ntini.
Swann is overwhelmingly superior to Harris, and Tahir is completely unproven at the top level.
Kallis is useful and is probably South Africa's 3rd best seamer, but since he's in the side for his batting I'm not factoring him in, as his main job is covering a pretty glaring weakness.
So that's two of the 4 where England are hugely superior, and 2 where South Africa are marginally ahead. In my book that gives England, quite comfortably, the best attack going. Look what happened to South Africa when Steyn had a bad series v Pakistan, and look at England when Anderson got injured at Cardiff. Huge difference.
That's not even taking England's bench strength into consideration. Name me one other Test side whos 2nd string attack has 200+ Test wickets between them.