Staying with Memcached
I am staying with Memcached, it's better anyway.
Who needs these turds like MongoDB and Redis anyway, too highlevel on one front, too low level on the other, too bloated and buggy on a third dimension. And now super complicated mess of licenses, not even open source anymore. So better stay away from them.
For in-memory, there is no better than Memcached or (SQL-DB offerings like SQLite inmemory). And there are better options for NoSQL front too. And for message queues there are battle harded better alternatives too.
What's really as bad is the dark communication pattern that Redis Labs does on HackerNews and Reddit, with help of Mods.
1) "Redis Labs Raises a $60M Series E Round" https://news.ycombinator.com/item?id=19202076
2) "Redis Labs Changes Its Open-Source License Again" (quickly banned from frontpage) https://news.ycombinator.com/item?id=19221754
3) replaced by official BS: "An update about Redis developments in 2019" https://news.ycombinator.com/item?id=19227070