wow good question, there are spatial trees in MySQL, the question here should be more about the properties needed not what's better -> does it need to be consistent ? sharded ? distributions ? size ?
SQL is still the most consistent standard database we have. and I takes less memory than ES ofc..... but if you need to shard it for high traffic and you can live with eventual consistency i would take ES or i would go for MongoDB which as a nice native interface for that as well.
j
stuff ;)