Worked at both. Both have problems and good points. At least Oracle is strongly in the Linux/Intel world; mainframe was the only part of CA that made a lot of money, although distributed had all of the interesting work. CA pretended to be a unified company; Oracle doesn't bother.
And I have no idea of how much of CA still exists after the acquisition/merger. The mainframe part will last as long as customers are willing to pay to maintain aging infrastructure; the rest is mostly irrelevant.