With any list like this are we talking peak value or franchise value.
I'd put Shaq ahead of Hakeem. He was unstoppable his peak years in LAL, where his game was at peak evolution and he still had most of his athleticism. If Hakeem doesn't win in 94 and 95 when there was no MJ, would he be rated as highly? I'm unsure. Maybe he doesn't get enough credit though - b/c people like me put an * next to his name. (Tangent: Actually a great what if is, if MJ stays, beats Houston those years. Wins one more and then retires leaving 97 and 98 titles to Utah. Really changes the perspective on Malone, Stockton, and Hakeem.)
Over the last thirty years of the feature centers:
1. Shaq
2. Hakeem
3. Kareem (post 80s)
4. Robinson
5. Malone
6 - 8 (Ewing, Mourning, Yao)
9 Howard
Parish, Dikembe, Wallace weren't feature guys, I don't think they belong on the list.
Howard is like super Dikembe - good enough he can be a bad feature guy, but not a good feature guy.