Before Dwight Howard decided that he wanted out of Orlando, another center desired the exact same thing. That center achieved many things with his new teams, and some of those achievements will not be easy for Howard to match.
The Orlando Magic selected O'Neal with the first pick in the 1991 NBA Draft and did the same with Howard in 2004.
Both players had what should be considered successful tenures with the Magic, but both left the team under unfavorable circumstances. The way in which they left has and will always tarnish the level of success that they had in blue and white; that is one thing that both centers share.
While Shaq is undoubtedly more talented offensively than Howard, the latter makes a far bigger impact on the defensive end of the floors.
Honestly, it would have been a spectacle if these two behemoths could have faced off in their respective primes.
Since that is impossible, the next best way to compare the two is to put their seasonal achievements side-by-side.