Here is my top 5 and reasons why.
Sure Olajuwon is a great player, But you got to take the fact that Abdul-Jabbar was 38 years old when Olajuwon entered the league at 22 years old in 1984-85,But still Kareem played him pretty even in there meetings until the last couple of years before he retired at age 42 in 1989. Olajuwon's career really declined the last 3 years big time at the age of 38.
#1 Kareem Abdul-Jabbar, The ALL-TIME NBA leading scorer, The most SEASON MVP'S with 6 (Jordan Had 5) Also made the NBA first team 10 times in 20 years, more than anyone and won 6 championships, No doubt he was the best. Plus was the oldest playoff MVP at the age of 38 when his lakers defeated the celtics.
#2 Wilt Chamberlain, He has the 2nd best scoring average of all-time with 30.1 points per game and average almost 23 rebounds per a game with 22.9 in his 14 year career. Basically holds all the records, But this was against several players who are much shorter than him. 4-time season MVP also won 2 nba championships, No one ever out played him except for Jabbar, Well some will say Russell was better, But not true it's just that russell had a much better team with several hall of famers in it.
#3 Bill Russell, For his career he only average 15.1 pts per a game and 22.5 rebounds per a game, But what made russell so great was he made all his team mates around him into better players, Probably my opinion the best shot blocker and the most important thing 11 CHAMPIONSHIPS WON IN 13 YEARS. He also was a 5-time season MVP as far as playoff's MVP they didn't count those records until after he already retired.
#4 Hakeem Olajuwon, I believe holds the record for most shot blocks but they didn't really count all the block shots in Kareem,wilt and russells careers, but no doubt Olajuwon is a great defensive player. Olajuwon only manage to get in the NBA finals only 3 times winning 2 just like Wilt. He is in the top 10 in all-time scorers, Only reason I don't rate him higher than russell is well he only won 1 season MVP to Rusell's 5, and plus russell won 11 championships and Olajuwons teams didn't have that many great seasons during his long career there.
#5 Shaquille O'Neil, If this guy could at least shoot 80% in free throws well I would rate him #2 behind Jabbar. 3 time playoff MVP, 1 time season MVP, he still has at least 5-8 years left in him who knows how many more championships he might have. It's premature to put him in this list as his career has not ended, but in the past 8 years there is no doubt he has been the most dominating center to date.