Some of those DBs solve different use cases than others. I wouldn't use Redis as an embedded DB (unless benchmarking indicated it fit my needs better), as the user of that software benefits most in using it with multi-machine access in mind. Embedded use cases are where RocksDB, LMDB, TokyoDB/KyotoDB, SQLite, etc. come into play.

Keeping the use case in mind (and it's possible evolution) will help pick the best tool for the job.