I agree that the better argument is McGrath vs Hadlee. For me, McGrath was the better bowler but as an overall package Hadlee was the better all round cricketer. With a team with a a weak batting line up, Hadlee would have to be preferred, for for the team that McGrath played or even an ATG team with Imran (or even just Marshall and Warne behind Gilchrist) I would go with McGrath.
One also have to question the secondary roles of players when it is not to a high standard. While Hadlee's/ Imran's batting and Sobers bowling were critically important to their teams it was made more important due to the frailty of Pakistan's and New Zealand's batting and the periodic weakness of the W.I attack. Marshall was seen as a handy and talented batsman, probably at least the equal of Hadlee, but because of the strength of the W.I batting, he didn't always take it as seriously as Hadlee and Imran had to (especially after Imran's injury) but when it was required, he stood up and performed.
In an ATG setting, Sobers/ Kallis bowling would be handy even useful and required (might even snag a wicket or two, but hardly match winning. Similarly Imran/Hadlee batting, If Bradman, Sobers, Hobbs ect failed and collapsed, don't see what Hadlee (his two hundreds came vs Sri Lanka and in a umpire tainted match vs W.I where even he admitted they gave up and it didn't mean as much) or even Imran would really be able to do. I have previously argued that secondary skills that are ATG quality, Sobers, Hammond, Chappell, Kallis slip fielding for example would be of greater value in an ATG team than their bowling or Imran/ Hadlee batting as they would be required to take any/all chances and even create chances from half chances. I acknowledge that argument is scoffed at here, but growing up watching the great W.I teams and then the Aussie units, the cordons were more consistently important to the teams success than the bowling of Richards, Border, Waugh etc (though a Kallis or Sobers would have definitely been a welcome plus) or the tail wagging of the lower orders. The only time the tail collapsing came into focus was when the top order was much weaker and left the burden to the tail to pull them out of the fire.
Finally for all of the great performances of the great (bowling) all rounders of the '80's the best team didn't have one, similarly for the Aussies that followed them. Handy yes, more so though a great batting all rounder to spell your primary attack, keep the run rate low and sneak out wickets if the batsmen relax but not to the extent that their virtues (in particular the bowling all rounders) are extolled.
Just my two cents worth.