I would say out of the bowlers i have seen since the 90s it would have to be Wasim Akram.
From the older generations I guess it would be Malcom Marshall based on the video footages I have seen of him as well his stats.
This is my criteria
Pace: Wasim had plenty of pace even during the later years with a shortened run-up
Swing: He was the absolute master of swinging the ball both ways in any condition
Accuracy: I have rarely seen him get hit for sixes, he generally maintained a superb line and length always attacking the stumps always looking for lbws
Variety: He knew how to bowl every delivery... the special one was the reverse swinging yorkers he would bowl at the death overs in ODIs and also in Test cricket to the tail enders.
Fitness: He is one guy that rarely got injured even though he played in both ODI and Tests