well, you dont get certifications just to get certified..its knowing your strengths that could be harness in full swing specially in a fast paced environment of technology, get certifications that really suites your needs..lets say you have taken oracle certifications, question is would it benefit you in the future?that you know in yourself you dont have the knack on programming..itsnot im discouraging you to take certifications..it yourself who could answer this questions..whats best for you
Two are different certifications, one is Database and anotehr is OS. If you want to move on the Data base direction then definitely Oracle is better . If you are planned on Linux administration then Red hat is better. Oracle with Redhat is very good for DBA, if not atleast Oracle.
So decide your career then choose.