In my opinion both were great, Imran has a little edge just becuase of his leadership.
I remeber reading an article by Munir Hussain, where he was comparing both Imran (87 runs, 9/136) and Botham (2 runs, 6/156) and after Tahir Naqqash’s performance (51 runs, 6/86) in first test where Imran was Man of the Match Munir’s response was even Tahir’s performance is better than Botham in this particular test.