Duncan has more MVPS, FMVPs, more playoff appearances, more All Star selections, more All-NBA first team and total selections, more all defensive first teams, and was better for longer.
Hakeem's Prime was better but consistency and longevity matters.
Duncan has also played with at least two hall of famers for 95% of his career, whereas Olajuwon has only played with a Hall of famer during the beginning and the towards the end of his career,
Finals MVP results greatly from the organization, you can't have shot at it unless your team is good enough.
Lets examine the numbers:
Olajuwon was the better offensive player than Duncan, finishing with
26946 career points to Duncan's
26496, despite Duncan playing two more years than Hakeem.
Hakeem also finished with a better FG% than Duncan (
51% to 50%) despite being more of an offensive focal point throughout
more of his career,
Olajuwon also edges out Duncan in rebounds averaging
11.1 to Duncan's 10.8. Duncan's rebounding total is higher, but that's because he played two more years, Hakeem was more than capable of sticking around two, three more years.
On Defense, Hakeem absolutely destroys Duncan, finishing with
3,830 blocks - best ever (since blocked shots were being recorded) that's good for 3.1bpg to Duncan's 2.2 blocks per game, good for 19th place in NBA history. Duncan finished with
3020 blocks despite playing almost 210 more games.
Olajuwon doubles Duncan in the steals category with Olajuwon finishing with
2162 career steals to Duncan's 1025 total steals, so he probably had better hands playing the defense below the waist. Again Duncan played 200+ more games than OIajuwon.
Hakeem was a better FT shooter,
71% to Duncan's 69%.
Duncan's beats out Hakeem in assists
3.0 to Hakeem's 2.5, which I believe had more to do with Duncan being surrounded by better players than Olajuwon for a longer period of time.
Hakeem was also ranked number 1 in defensive rating 5 different seasons (
86-87, 87-88, 88-89, 89-90, 90-91), Duncan came number 1 in 4 different season, despite playing more seasons (
04-05, 05-06, 06-07, 12-13).
Overall Hakeem was better offensively, defensively, on the boards, better shooting touch, better footwork. Duncan had the advantage of playing for a better organization. Switch roles and it's not hard to imagine Hakeem winning 5 titles with the Spurs.