There isn’t a single document that lists the pros and cons of RxJava versus Reactor. We don’t see it being a mutually exclusive relationship. If you need the holistic Reactive approach of RxJava Observables, then use that and maybe add Reactor as a Scheduler implementation to get the high speed dispatching. If you’re more interested in the functional, low-latency, lambda pipeline approach, then maybe choose Reactor as the foundation with the option to add Observables as the payload of objects passing through the Stream.
Each has its strengths and weaknesses and you just have decide, based on your understanding of what those are, what the final balance is. No one can tell you that and any attempt to do so would be disingenuous to say the least.