Solr. The correct answer is Solr. All the search features of Elasticsearch (both are built on Lucene, which provides the actual search implementation) without the problems that Elastic (the company) or Elasticsearch (the product) brings with it. 99% of companies using Elasticsearch would be far better of with Solr.
Solr will work perfectly if you want to do a standard search (db, shop) or need a customized approach, like custom transformers, ranking, etc. However, if you aim for "something that just works good enough" and has much better scaling capability and tooling, you can't beat ES/OpenSearch here (Solr scaling is much more manual process than ES/OS). And if you want to stay away from ElasticSearch drama, stick to OpenSearch - they are shipping excellent stuff these days.
Solr is seen (probably unfairly) as passé by many people.
I used Solr back in 2008-2009 or so and it did a great job, but people didn't like that it used XML rather than JSON. Then we had a requirement for something like Elasticsearch's percolate query functionality, which Solr didn't support. So we switched, and subsequent projects I've joined have all used ES.
So now in addition to the "does it do the job?" question, teams might also ask "can we hire and retain people to work with this technology rather than the more popular alternative?".
