In Huifan thoughts, each method has its own advantage and also disadvantage.

Fingerprint: The most applied with lower cost, but the security level is low.
Face: Higher security than fingerprint, with time going, face may change keyless entry door locks and hard to Paxton Access recognise.
Iris: Highest security but with the highest cost.

In conclusion, based on your role based access control example barget ,find the most suitable biometric way.