Oracle Linux vs RHEL, which is better?

Oracle Linux has evolved as a true enterprise Linux for enterprise-class loads. It has everything Red Hat has plus few additional features. There are key enterprise-class features like ksplice, dstrace etc, however, your decision should consider technical and business aspects. If you are running Oracle workload then it would make sense to run it on Oracle Linux as you get a single vendor support. Oracle has a better method of licensing and you can optimize the cost.

It depends on the applications you are running on your linux system, in our environment we chose Oracle Linux (known before as Oracle Enterprise Linux "OEL") over RHEL because we are using multiple Oracle products to support our essential business requirements in financials, procurement, logistics and enterprise resource planning. These products are designed, engineered and tested to work together and to avail distinct advantages in running Oracle databases and applications on an end-to-end Oracle solution stack.

We can maximize the OS features like Unbreakable Enterprise Linux (UEK), ksplice zero-downtime updates, dtrace for Oracle Linux, clusterware, KVM, it support also the Red Hat scalable filesystem and the most important was the support and services you can get from Oracle such as updates and patches.

As everybody probably knows, _better_ is a hard word.
Any comparison must be based on your own use to the system.
I remember - some years ago - about licensee in Oracle, that let you run Oracle in Virtual sockets as physical ones, but only in Oracle Linux virtual platform or in (Sun) Oracle hardware. In any other case you must pay for all the physical processors you have in your machine.
That was my own "better".

We have been using both OEL and RHEL. We have been very Stable with RHEL and have had no issues with running the Oracle stack and SAP stacks on it. Support is a must if you run into any issue, so make sure that you have proper support subscriptions in place.