As Vitalik said, most of GP's message is wrong. The trusted setup was participative, as in anyone could participate and as long as one person was honest the protocol was secure. I know people who participated, I think it's FUD to say that the trusted setup is not great if you're getting value from it (short-size proofs).

Furthermore zk-SNARKs are the best constructions out there for confidentiality, not ring signatures, as was demonstrated many times on research on Monero

tl;dr monero does not provide that much confidentiality because the anonymity set is too small. In other words, you are only hiding your transaction among multiple ones, whereas Zcash hides your transactions among all the set of accounts.