Beam Privacy has compared ZCash, Monero and BEAM by looking at three parameters: confidentiality, scalability, and auditability
Monero scores very good on confidentiality, poor on scalability and poor on auditability as well.
Zcash has great privacy features, but they are computationally heavy and see little use so far. Zcash scalability is better than Monero’s, but still poor, and the auditability is poor as well, although Zcash has plans to improve it.
By implementing Mimblewimble, BEAM achieves excellent confidentiality and scalability, and the extensions to the protocol allow for excellent Auditability as well.