Both players played for Lakers, and of course you all know that. But who was the better player? I'll explain it.
I would have to go with Wilt.
I was Kareem's biggest fan when he was playing in the NBA, but I was also Wilt's biggest fan just prior to Jabbar's emergence. When they played against each other, I rooted for Wilt and the Lakers.
They played against each other 27 times, including 11 games in the playoffs of 1971 and 1972.
Chamberlain's teams won 14 of the 27 games, while Jabbar's teams won 13.
Wilt had 122 50-point games, Jabbar had 10. One of those was against Wilt, but the Lakers blew the Bucks out of that game, 123-107.
In their first 11 meetings, Chamberlain was still able to (i.e. inclined to) score with Jabbar. In those first 11 games, Wilt averaged 22.8 ppg and 17.6 rebounds, while Kareem averaged 26.0 ppg and 15.6 rebounds.
In the 1972 season, Kareem outscored Wilt 201-70 in their five regular season games. In the six 1972 playoff games, Kareem outscored Wilt 202-67, but Wilt out-rebounded Jabbar and played better defense (i.e. shutting down the middle) when it counted.
Chamberlain himself went on an offensive tear in Game Six (bringing the Lakers back from a 10-point deficit), and led the Lakers to a series clinching victory, ensuring there would be no Game Seven.
Jabbar's 39 points and 20 rebounds led the Bucks to a 120-104 victory on Jan 9, 1972...this ended the Lakers' record 33-game winning streak, the longest winning streak in the history of professional sports...
Jabbar might have a slight edge in "clutch" play—his skyhook was the most unstoppable shot in the history of the NBA, by far. Jabbar was also a better free throw shooter, and made a great many clutch free throws during his career. Kareem also won six rings to Wilt's two.
However, Wilt played on what may be the two greatest teams ever, the '67 76ers and the '72 Lakers...the Sixers of 1967 were probably the greatest single season team ever.
But, given his incredible numbers, stamina (Wilt averaged over 45 min/game over his career), and impact on the league and the game itself, I would have to give Wilt an edge over Kareem.
50 ppg, 30.1 ppg over his career, 23 rebounds/game over his career, the only non-guard ever to lead the league in assists, 100 points in one game, the list goes on...Wilt was simply more dominating.
Also, Wilt retired while he was still a star in the league, having led the NBA in rebounding during his final ('73) season. Jabbar was a mere shadow of his former self during his last two to three years (even still, the Lakers won two championships in his last three years...Kareem won rings at the age of 40 and 41, but lost in the finals at the age of 42).
They actually both lost in the NBA finals in their final seasons.
An in-his-prime Wilt would have destroyed Kareem with superior strength, leaping ability, and stamina—not to mention awesome offensive and defensive skills.
Wilt was able to block Kareem's skyhook on occasion, and he did an outstanding job on Kareem in the 1972 Western Conference playoffs...so much so that when the Lakers eliminated the Bucks in the sixth game in Milwaukee, the Bucks fans gave Wilt a long standing ovation for his work against Kareem during that series when Wilt left Game Six for the last time.
There's a video on YouTube which shows Wilt blocking a right-handed skyhook by Kareem, and then a few seconds later (after a couple of other highlights) shows him blocking a left-handed skyhook by Kareem. What you can't tell on that video is that the two blocks took place on the same trip down the court.
Wilt first blocked Kareem's righty hook, and the ball went into the corner. Kareem retrieved it, and drove across the middle and shot a lefty hook at Wilt, but Wilt blocked that shot as well. (The entire sequence with no cuts is also somewhere on YouTube.)
The second of the two blocks I just mentioned occurs at about 2:50 of this video.
Here are some covers of LIFE magazines from 1972...check out the March 24, 1972 cover: "The Greatest One-On-One Match in Sports—Wilt vs. Kareem" (hopefully the link will work).
I have that issue...basketball almost takes a back seat to the actual subject of the article, which is the completion of Wilt's house overlooking Los Angeles. But the issue has some nice photos in it.
Wilt and Kareem have some similarities in their style if you compare Kareem to a young Wilt. When Wilt came into the NBA, he was not as massive as he later became...he was built more like Scottie Pippen than Shaq.
But one of the things they had in common was that they didn't want to be known as just big guys who could dunk. Wilt did not dunk that often in games, he preferred the fade-away jump shot or finger rolls. Kareem, of course, preferred the skyhook.
Both guys could put the ball on the floor, and were great passers.
Kareem's main advantage over Wilt during the years they played against each other (1971, 1972, and 1973, Wilt was injured for just about all of Kareem's rookie 1970 season) was age. He was about 11 years younger than Wilt. They faced each other 27 times in those three years, with Wilt's Lakers owning a 14-13 advantage over Kareem's Bucks.
Kareem did well statistically against Wilt, and admitted that he did in fact play harder against Wilt than he did against anyone else. Kareem simply explained that if he didn't play extra hard against Chamberlain, "Wilt would have destroyed me" (even at his age).
Wilt's strength was legendary...Gus Johnson (a 60s, early 70s version of Charles Barkley) suffered a dislocated shoulder as a result of trying to dunk over Wilt.
Gus went flying in from the right side at a 45 degree angle, Wilt caught the ball cleanly with his left hand, threw Johnson to the floor, and dislocated Gus' shoulder in the process. Johnson became the only player in NBA history to suffer a dislocated shoulder because of a blocked shot.
Wilt also broke Johnny "Red" Kerr's foot with a dunk. The ball hit the floor (actually, Red's foot) with so much force that it broke some bones...Kerr immediately knew what happened. He started up the court, pretended to trip, and left the game because he didn't want anyone to know that Wilt's dunk broke some bones.
So YES, I pretty much DISAGREE with ESPN list about top 10 centers of all time. When it comes to basketball history, ESPN is clueless. (If you wondering what list I'm talking about, check this out.)