I voted imran as well. If kallis was bowling on fire he would have been bowled more to take 5 wickets. A captain would keep a bowler that had taken 3 wickets in the attack.
Imran's batting stats suffer a little because he came in so young and not fully developed as a batsman, but regardless, his bowling was as good as Sobers batting, easily one of the best 10 ever, if not top 5, and his batting was more than good enough to play in any top 6 at the time.
I think an all-rounder that averages 20 with the ball and 40 with the bat is more useful than one that averages 30 and 50, although I guess while Kallis batted in a batting friendly age, Khan bowled in a bowling friendly age and while he bowled on flat tracks he did have the somewhat, shall we say generous, home umpires.
but anyway, the man was a genius. plus if we're talking all-rounder proper, not just a combination of batting and bowling Imran was also a brilliant captain ( I guess it should be said that Kallis is an excellent slip fielder).