Rate Wasim above Imran as bowler ?I share view but would like your reasons.
I actually don't rate players, with stats only. For Fast bowlers, it's more about completeness, and versatility over a longer period, rather than average & SR.
Wasim is probably the most complete bowler in history of the game, who had every skills - conventional or reverse swing, cut, in/out swing, deadly yorker, silent bouncer, cutter ... and he could do that at pace. I have seen him swinging it away & cutting back off the seem in one ball - that Allen Lamb bowled would have been hyped as the ball of millennium had it been from a bowler with cricket media monopoly. In that regard, Was is actually unique, because all the fast bowlers listed here - most of them were hit the deck type. They were extremely skillful, cunning, aggressive and they could set up batsmen, could use condition, could choke batsmen, could fright them; but Wasim was probably the only one with one advantage - at his fittest, he could match any of them in pace, but no one ever will match Wasim in swing. 1st over of 1996 Hobart Test actually tells what he was - that too at his semi decent pace. He & WY had to plan their entire attack on getting batsmen out keeping slip cordon out of equation, therefore Wasim's stock ball was targeting stick, rather than using that incoming ball as a surprise element.
His average of 23.6 is actually misleading - apart from PAK's fielding & drop catches, he bowled over 900 No balls in career - before 1960s, those won't have gone against his stats, while from 1990s, there is a double impact - No balls are scored off in addition to runs scored by bat (that 5 goes against bowling if a boundary is hit of a No ball). This is something cost Ambi & partially Donald as well, but Wasim was at least 3 times loose when it comes to no ball. Being a chronic diabetic (& he had off field involvements), he was probably never more than 75% through out 90s, still for most, he was the cricketer of the decade, that tells everything.
Coming to Imran, he is my most favorite cricketer and excluding the top 2 given spot, most neutral cricket enthusiast would rate him the greatest ever Test cricketer, may be over all cricketer as well, for his contribution to team, influence on a match in 3 folds & both formats that he played - with bat, ball, with leadership & his fighting qualities - and all these after losing best 2/3 years of career at the best age (31-33, which in standard case 27-29, officially). But, he wasn't the complete fast bowler; rather I would say he had few deadly weapons, which were absolute unplayable for his best 5 years. And, he earned that stats - it was 1970s & 80s, not much free lunch.
I explain it this way - take other 4 top fast bowlers (I have taken out Mac, Hadlee, Truman & Styen for that qualifier - fast) - Marshall, DK, RR Lindwall & Wasim - their dismissal chart is much more diversified - from caught at slip to gloved at gully to LBW without offering. For Imran, his dismissal chart is limited, because, in his rhythm, that deadly swerving in-deeper was absolutely un-survivable, but he wasn't complete. He actually would have got lot many wickets had DRS been available that time, because those days Umpires were reluctant to give LBW on big swinging balls. But, as a fast bowler - show me his leg-cutter, conventional out swing, off-cutter with old ball? For someone like Marshall, he used his off-cutter with semi old ball almost like a spinner & brought his short cover in game; I have seen right handed batsmen getting bowled playing inside the line of DK's leg-cutter and both could get batsmen out LBW without offering. Imran's pick was exceptional, but not his versatility, his completeness - it's like the mystery bowlers, but his mystery was too good; batsmen knew it was coming, but didn't know how to counter that.
In this discussion, I must have to mention one bowler, who is the most hyped in history -Syd Barnes, and it's not because he was born 140 years back, playing in 1900-1910 era. People get impressed with his 189 wickets in 27 Tests (And average of 16), because they don't know the full story. Out of his 189 wickets, he had 85 (?) at <10 average and freakish SR, against SAF of 1900s - some of the Tests should be discarded from it's status because of the quality. Against AUS, in 21 Tests, he had 104 (?) wickets in 21 Tests at 21+ average, which was actually ordinary for that era - apart from Hobbs, with 58+, only 2 batsmen averaged over 35 in that era with 25+ Tests, were Trumper & Hill. And, Trumper didn't play in couple (?) of Ashes tours that Barnes played. Hobbs debuted in 1907 (Barnes played last FC in 1912) - with his 58+ average before WW1, he was actually equivalent to what was Bradman 20 years later - against whom Barnes hardly bowled even in FC. British cricket media tries to hype Syd Barnes for his skills (he was listed medium fast in 1900s, so I guess many here in PP would have out paced him), but in that regard George Lohman, Tom Richardson & Demon Spofforth should also be considered.
I completely agree with your list & order, with that qualifier - Ray Lindwall will make my XI over Truman as well, but Fred Truman was probably the best ever in English condition (in a time less world). I am not sure whom I'll pick at 6th - Roberts, Holding, Waquar or Donald.
: 1) Jasprit Bumrah : 64 Wickets @17.15 2) Kapil Dev : 51 Wickets @24.58 3) Sarfaraz Nawaz : 50 Wickets @31.46 4) Imran Khan : 45 Wickets @28.51 5) Wasim Akram : 36 Wickets @24.05 6) Mohammad Shami : 31 Wickets @32.16. Bumrah is the Greatest Bowler from South Asia in Australia 
: 1) Wasim Akram : 53 Wickets @28.73 2) Ishant Sharma : 51 Wickets @33.35 3) Mohammad Amir : 49 Wickets @25.55 4) Imran Khan : 47 Wickets @24.63 5) Waqar Younis : 45 Wickets @27.48 6) Jasprit Bumrah : 37 Wickets @26.27
