It's not even a contest, it simply has to be Imran Khan. He has 362 Test wickets at 22, twenty-two! That's better than Wasim, Waqar and Walsh and as good as Donald and Hadlee. Add to this the fact he made 3,807 Test runs, averaged 37 with the bat and made six Test hundreds and here's a player good enough to get into most Test top sixes as a batsman alone.
And what of his other attributes - he not only captained, but united, the most fractious international team going and moulded them into the only side who gave West Indies a contest throughout the 80s. And how about his legacy - Wasim Akram, Waqar Younis, Inzamam-ul-Haq and Mustaq Ahmed all owe their international careers to Imran's faith and insistence on young talent. Togethar they made up the backbone of the Pakistan side throughout the 90s and into the 2000s. Oh, and then there's the small matter of the most incredible, thrilling backs-to-the-wall World Cup victory campaign ever seen in 1992.