If you have to choose between one, then yes; full disk encryption is superior. But they should ideally be used in tandem.
Without secure boot, you are vulnerable to evil maid attacks. A bad actor can modify your bootloader (which has to remain unencrypted) in a way that allows them to steal your encryption keys. Secure Boot prevents running unsigned bootloaders, which negates this risk.
If you have to choose between one, then yes; full disk encryption is superior. But they should ideally be used in tandem.
Without secure boot, you are vulnerable to evil maid attacks. A bad actor can modify your bootloader (which has to remain unencrypted) in a way that allows them to steal your encryption keys. Secure Boot prevents running unsigned bootloaders, which negates this risk.