S/MIME and OpenPGP can both sign and encrypt message content, but they commonly use different trust and key-management models.
S/MIME is certificate-oriented and often fits organizations that already operate PKI or managed certificate services.
OpenPGP uses OpenPGP keys and has historically relied on different key-distribution and verification practices.
Choose for the environment
The algorithm list is not the whole decision. Consider client support, external recipients, key recovery, revocation, identity proofing, automation and administrative overhead.