I'd also include redis because of the graph module (https://oss.redislabs.com/redisgraph/).
I've likely missed a bunch of others. Add them as I'm interested in graph db and have only scratched the surface myself.
OrientDB is an alternative to Neo: https://orientdb.org/
There are a bunch of DB's compatible with Tinkerpop and e.g. query-able with Gremlin: http://tinkerpop.apache.org/
And this awesome page has some good entries: https://github.com/jbmusso/awesome-graph/blob/master/README....
I'd also include redis because of the graph module (https://oss.redislabs.com/redisgraph/).
I've likely missed a bunch of others. Add them as I'm interested in graph db and have only scratched the surface myself.