Well, Horry played with Hakeem, Shaq and Duncan when each was at their primes... and won titles with all three. So if Horry says Hakeem was better than the other two... can't really argue with that as he would know best.
Personally, I think Hakeem is probably the best big man to ever play the game. Best 1-on-1 skills and footwork on offense, and the best defender too. One could make arguments for putting Wilt and Kareem over him because their primes were in a different era... but he is the best big I have seen after the NBA and ABA merged. It is quite criminal that people rank guys like Shaq and Tim Duncan over Hakeem in the all-time lists. Especially Duncan, since Shaq was dominant in his own right because of his size. Duncan was like Hakeem-lite, similar to how Kobe was like Jordan-lite. Both were great players but did not peak as high as the originals. Hakeem would have burned Tim Duncan (who was too slow to keep up with Hakeem) if they came into the league at the same time, and probably would have burned him worse than he did to David Robinson.