Marshall - generally regarded as the best, an opinion I'm sold on. Could swing it, had genuine pace and once Lillee taught him how to bowl a leg cutter, he pretty much could do it all.
McGrath - point of difference with his height and bounce. Averaging 21 while playing for most of the 2000s when decks are regarded as being crazy flat gets you a lot of points imo. Batsmen of that era get marked down because it was easy, he should get marked up because it was hard.
Akram - Went for the left arm option here because I'm looking at how they'll operate together rather than necessarily picking the three best individuals, though he would be in the argument in that case anyway. Express pace, conventional and reverse swing, wicked bouncer and yorker. Just shades Paddles.
Of all others, not just those on this list I think Steyn, Lillee, Davo, Ambrose, Imran, Cummins and Garner are all unlucky. Nearly went with one of the latter two as they're arguably the best first change bowlers of all time. Bumrah could end up in the argument too, but he hasn't played enough tests yet. Terrific bowler though.