When I found out how powerful PostGIS was, I was gobsmacked. No matter how ridiculous that sample data I'd provide, the results would be fast and come back accurate and consistently.

The only other database engine that offered decent GIS indexing and searching, was ElasticSearch. But ES is not an ACID adhering engine, and is specifically designed to be a screaming fast fulltext search engine first, and everything else second. You never want ES to be your primary database engine (it's not designed for that anyways), it should always be a compliment to your more stable and consistent database solution.

Simply put, I could have stuck to a MySQL + ElasticSearch solution, but the operating costs around that get astronomical when you get down to ho HEAVY ElasticSearch is, and how expensive it is to operate in the any hosting solution.

PostGIS allows to me not need ES for geospatial indexing and querying, and to be really fast at it while doing it. A god send.