The choice between UNIX and Oracle certifications (classes) is really a choice between which path you want to pursue. Personally, I would recommend the Oracle classes. With the Oracle classes, you will get training on creating and administering Oracle databases. I would say that their is more demand for Oracle trained professionals than UNIX trained professionals. Getting UNIX training would be beneficial if you wanted to administer UNIX workstations and servers. So, if you want to work with data and databases, then go for the Oracle training. If you want to perform workstation/server support, then go for the UNIX training. Also, if you want to get Oracle Certified Professional (OCP) certified, then you have to take at least one official Oracle class, whereas you don't have to take a Sun class in order to get UNIX certified.