I notice updates with RHEL to CentOS take awhile. When it comes to down being up to date, Ubuntu/Debian wins.
Honestly (#LOGIC), Ubuntu is used more in the Desktop world. Which means more users will be using java on Debian/Ubuntu more than CentOS. Which promotes for more errors to be found and fixed vs CentOS. I'm not saying I'm correct, it's just a theory.
Basically In a nut shell, Java would be more stable on Ubuntu/Debian vs CentOS