Olajuwon was one of the best defenders of all-time and still has the blocks record. Durant is serviceable.
Olajuwon is one of the greatest playoff performers of all time taking a poor team and winning a title.
Olajuwon is one of the best rebounders of all-time.
Kevin Durant couldn't win a title with 3 MVPs (including him) on his team (and only made it to the Finals once).
He instead won his only titles when he joined an already accomplished Championship roster. Teams geared up to stop Steph as you had to. Durant came and went and Curry won another title after to go along with the one before.
Durant has handpicked his location the past few years and how far in the playoffs has he gotten? Not very far.
Who are Durant's non-Warriors teammates that he has struggled with: James Harden, Russell Westbrook, Devin Booker, Kyrie Irving, Bradley Beal...the list goes on.
I would take Olajuwon 10 times out of 10 times if I were picking between the two.