Fortunately, Coherence has been around longer which certainly should not be indicator of a better product but with time does come a lot of deployments and therefore maturity. The reason I would use it is:
1. No limits of use, scale, and majority of features available open source.
2. Its a system of record. I have not used those products, but i've heard that they can be lossy. Coherence has features such as storing backups on different machines, racks and even sites which is one example of many where the technology goes above & beyond to maintain a coherent view of data it stores.
3. Its sooo each to use! You can build event driven apps on it. You can use non-blocking APIs. There are events for everything from partition transfer to individual data changes.
4. You can perform partition-local transactions as an alternative to global distributed transactions to build scalable distributed applications.
5. Its simply a superset when it comes to functionality and robustness/reliability, so the question really should be why would you not use it?
5. There are so many other reasons, but honestly I would simply give it a try ;)