I'm obviously biased since I am a Hibernate developer, but I can at least provide some elements focused on Hibernate Search. As to which is "better", that's for you to judge.
The main difference is that Hibernate Search provides integration between JPA and your index of choice (Lucene or Elasticsearch):
- Hibernate Search will automatically add/update/delete documents in your full-text index according to changes in your JPA entities (as soon as you commit a transaction).
- Hibernate Search will allow you to build a full-text query (full-text world), and retrieve the results as managed entities (JPA world).
As far as I understand, Spring-Data-Elasticsearch is focused on accessing Elasticsearch and has no JPA integration whatsoever. That is to say, you can use Spring-Data-JPA, and you can use Spring-Data-Elasticsearch, but they won't communicate with each other. You will have two separate models, which you will update and query separately.
Some other elements:
- If you don't need a distributed index, Hibernate Search can run in embedded Lucene mode, without all the Elasticsearch stack. It will probably be more lightweight.
Hibernate Search is currently not very flexible when it comes to customizing your Elasticsearch mapping or using advanced Elasticsearch features, because of the abstraction layer. EDIT: That's no longer true now that Hibernate Search 6 has been released.
- A Spring-Data-HibernateSearch module has been worked on in the past, but is no longer actively maintained: https://github.com/snowdrop/spring-boot-hibernate-search-booster