Hoopshype had an article about Kareem's bona fides for GOAT. And one knock was that there weren't other great C's in his prime. But I think that's a phony argument.
Kareem had a few years overlap with an aging, still dominant Wilt. Same with Willis. Nate Thurmond was still a mofo the first 5 years of Kareems career.
Wes Unseld was both Rook of the Year and MVP the year before Kareem entered the league, so their careers coincided. Wes took his team to three '70's Finals.
Cowens was another almost exact contemporary of Kareem's. Cowens averaged 18 & 14 & 4 in 10 seasons with BOS. Also won 1 MVP and was Top 4 in MVP votes three other years.
Bob Lanier, Artis Gilmore -- these were big tough dudes.
Lanier's career started the year after Kareem's. Career 20 & 10 guy.
Bob McAdoo played a lot of C and was a scoring machine. Won an MVP.
Artis started a year after Lanier (2 after Kareem) but ABA-ed it for 5 seasons.
So he was a mid/late rival to Kareem.
As was Bill Walton, a major force for a few years. Then there was a dominant Moses Malone.
Seems like a helluva lot of great Big C's in the 70's, to Bo.
In fact from 1970 (Willis) to 1980, only C's won the MVP award (5 of 11 times it was Kareem).
I think Kareem gets devalued somewhat because he only won 1 title as The Man. And was 2nd best to Magic on his 5 other title teams. And the 70's was a bit of a lull in the NBA, without a dominant team, before the revival ushered in by Bird & Magic (and the Celt/Laker dominance/rivalry).