Both Postgres and SQLite have extensive geospatial support (PostGIS and SpatiaLite respectively), including indexing and boatloads of useful geospatial function

Both Postgres and SQLite have extensive geospatial support (PostGIS and SpatiaLite respectively), including indexing and boatloads of useful geospatial functions. And in my experience, both of them are far more advanced than Mongo's geospatial support.