Older players like Neo4j Community Edition have some limits that require upgrading to an Enterprise license. ArangoDB supported graphs but recently changed their licensing. OrientDB was acquired by SAP and is withering while it's fork-replacement ArcadeDB doesn't have great connector support and seems untested. Apache AGE development has slowed due to business changes, etc. NebulaGraph seems reasonable, but there's surprising little feedback/chatter about it online.
What's your preferred graph database (preferably open source) and why?