Fingerprint
Fingerprint readers are mature and compact, but dirty, wet or damaged fingers and hygiene concerns can affect performance and acceptance.
Face recognition
Contactless facial authentication can be fast, but depends on camera position, lighting, image quality and presentation-attack defenses.
Iris recognition
Iris patterns can support high-assurance matching, while specialized hardware and user positioning may increase complexity and cost.
Palm and palm-vein systems
Palm systems may use surface geometry or subsurface vein patterns. Contactless options can balance strong authentication with high-throughput operation.
Use more than one factor
Combining a biometric with a secure card or mobile credential reduces reliance on a single modality and provides a recovery path when authentication fails.
Privacy and governance
Biometric templates require encryption, retention limits, access controls, a lawful processing basis and reliable deletion procedures. Unlike a password, a biometric characteristic cannot simply be replaced.
Conclusion
There is no universally best modality. Selection should reflect risk, environment, throughput, privacy obligations and user experience.