1. You want more robust security.
2. You want to avoid the steady stream of security updates required by using OpenSSL.
4. You are performance driven, and want to leverage the latest hardware crypto, or tune in progressive ciphers.
5. You want direct support for the crypto you use in MySQL or MariaDB.
6. You need FIPS 140-2 support for your MySQL install.
7. You want to use ChaCha/Poly.