One thing I wish redis had is the ability to extend itself beyond its memory capacity. So if I run out of memory, just move some stuff to disk. Or if I'm using persisted redis, just free up some memory.
Redis on Flash [1] is one of the key ways Redis gets people on their enterprise plan (esp before the SSPL relicense). I've spoken with their enterprise team before; it's ungodly expensive, even compared to AWS MemoryDB (wish I had the numbers on hand).
If you're looking for a Redis-compatible key-value store, kvrocks[1][2] is an excellent choice. We've used it in many projects, and it's proven to be very stable. Since it's based on RocksDB, it doesn't have the memory limitations of Redis and the license delirium ;-)
[1] https://redis.io/resources/building-large-databases-redis-en...