Wasim Akram's ability to weave a little bit of magic when you really needed it, ultimately gives him the edge. His ability to change the momentum of a game, and his brilliance in finals, is well documented. He was just a real game-breaker.
As for Ambrose, he was simply phenomenal and virtually impossible to dominate. He seemed like the type of bowler who took it to another level in big matches, when it really mattered. You had to see some of his performances in One Day finals in Australia, to fully appreciate how great he was. In both 88/89 and 92/93, he produced some epic performances in the finals series, including 5-26 and 5-32, to power the West Indies to victory. All up, throughout his career, he averaged only 17.3 in finals.
In the summer of 92/93, with a little help from Brian Lara, he virtually won both the
Test and One Day series, by himself. Seldom has one man, been so clearly the difference between two teams. You are talking about an opposition batting lineup that featured the likes of Taylor, Boon, Jones, Mark Waugh, Steve Waugh, and Border, and yet they were all completely powerless in the face of the onslaught from Ambrose. Very few fast bowlers in the history of the game, have been as dominant and as influential, as Ambrose at the peak of his powers.
The other guy who probably doesn't get his due in One Day cricket, is Michael Holding. I
remember reading a book about the One Day game at some stage in the 90s, and Ian Chappell rated Joel Garner and Michael Holding as the two best bowlers the game had seen, up until that point. With all of the focus on Garner, the greatness of Holding has been somewhat overlooked. In reality, their records aren't that far apart. In 98 matches, Garner took 146 wickets at 18.8, with a SR of 36.5, and an ER of 3.09. In 102 matches, Holding took 142 wickets at 21.3, with a SR of 38.5, and an ER of 3.32.
They were both great big match players, with Garner averaging only 14.3 in finals, and Holding averaging 19. Even now, you can still make a pretty sound argument, that they deserve to be ranked at 1 and 2 respectively.