I'd say your best option including support by Oracle Linux and the UEK kernel is BTRFS. To my knowledge there is no vendor or production level support for anything ZFS under Linux, and I've not seen any info that Oracle plans or was going to port and support ZFS in the future. Oracle has apparently invested into BTRFS instead.
Oracle does not currently offer ZFS as a supported product for Linux. If you use ZFS as provided, for instance, by zfsonlinux, it's up to you to look at license terms and determine the appropriateness of using it in your project. (And up to you to provide support for it.)
As suggested above, btrfs is the highly flexible filesystem which receives full product support on Oracle Linux, and it's extremely robust especially in the latest UEK5 kernels.