I use ubuntu server and that server has reported regularly for updates, while CentOS does not, my question is whether the use ubuntu security would be better?
Besides the frequency of updates, the choice of packages that get put in the distro in the first place is significant. If Ubuntu adds bleeding edge packages and then has to constantly patch them and CentOS puts up only stable line packages and only patches occasionally when security issues come up, the notifications would NOT be a good indicator of better security. I'm not saying that's the case, but your qualification is not a good test, and as Alpha01 said, security for two modern updated distros really depends on the administrator.
A server is always as secure as the good system administrator that maintains it. Thus said, simply because Ubuntu releases more updates on a more frequent basis, doesn't mean that it makes it more secure. Usually CentOS may take more time to roll out their updates, since they have to re-package the source rpm's released by Red Hat, while your getting the updates directly from Canonical.