With Shaq retiring, there has been a debate on TV and the interwebs about the top 5 centers of all-time. The word used to describe Shaq the most often during his career was "dominant," and Shaq was certainly that.
I have a problem with Bill Russell being mentioned as #1 by some people because you can't just look at the 9 championships. He is certainly a top 5 guy as he was the best defensive center of all-time and owned the glass, but not #1. Having the greatest GM/Coach of all-time, Bob Cousy, Tom Heinsohn, Sam Jones, and others around him along with there just being 8 franchises competing for a ring keeps him out of the top spot.
Some guys need rings to solidify their place in history. Kobe Bryant desperately needed to win a title without Shaq because he hadn't done it as "the man." There were at least a dozen players that would have won titles with the dominant Shaq from 00-02. LeBron needs one, but the number of titles doesn't mean you were a greater player than someone with a few less. However, I think you do need at least 1 to get into the discussion of greatest of all-time (see Dirk right now).
5. Hakeem Olajuwon - Hakeem has 2 rings (Finals MVP in both) and is top 10 all-time in points and just outside the top 10 in rebounds. He is considered the blocks leader, but blocks were not a calculated stat until the mid-70's. Olajuwon edged out George Mikan for the 5th spot due to his level of competition at the center position in the late 40's-mid 50's even though Mikan's 5 titles trump Hakeem's 2.
4. Shaquille O'Neal - Shaq gets on the list at #4 after winning 4 titles (3 MVP's) and finishing 5th all time in scoring. He is also 12th in rebounds and his run from 93-03 was the most dominant 10 year stretch anyone produced since the Russell/Wilt era.
3. Bill Russell - The greatest defensive center of all-time, Russell was a mammoth on the boards with over 20,000 career. Russell won 9 rings and was the force in the paint that the Celtics of the early to mid 50's lacked. He is 2nd all-time in rebounds and a 5 time MVP.
2. Kareem Abdul Jabbar - Kareem won 6 titles (2 MVP's) and 6 MVP awards en route to becoming the league's all-time leading scorer. He also is 3rd on the all-time list in rebounds and blocks.
1. Wilt Chamberlain - Wilt only won 2 titles, but that was mostly because he went up against Russell and his All-NBA teammates throughout his career. Swap Wilt with Russell and he wins at least a dozen championships. He was both a defensive presence, dominant offensive force, and all-around freak athlete. He is the NBA all-time leader in rebounds, 4 time MVP, 4th in points, and once led the league in assists just because naysayers said he didn't pass enough.