Wasim, Marshall, Warne, McGrath.
I went with the Wasim option, mostly because if a batsman saw off Marshall and McGrath then are Hadlee, Imran or Steyn really gonna pose them any new challenges? IMO not really, but Wasim most definitely would.
Outside of the change in angle, the other 3 are all capable of presenting challenges, but I guess Wasim's would be a unique one.
As I said earlier filling in Wasim is analogous to bringing in Smith for his left handed aggression, catching and captaincy. All added value, but worth the potential downgrade? Though admittedly Wasim is higher rated than Smith.
Imran to me is a little like bringing in Hammond for Sachin. Both still top 10 and quality players, though still a perceived, if slight down grade. Yes there's an offset, Imran being possibly the greatest no 8 ever, Hammond possibly the greatest 1st slip ever.
It is a quandary.
Order of skill as bowlers. (Mine and our ratings)
Hadlee
Steyn
Imran
Order by batting
Imran
Hadlee
Steyn
Steyn and Imran however were more renowned for reverse swing and were quicker, though neither set the world alight away from home. Though Steyn was better in India and the averaged about the same in Australia, but against much stronger opposition on flatter decks. England though, is a hole in his record.
Almost every option presents a compromise.
Except possibly the 4th, and that has only one vote, lol.