There is a different security profile on zkSync account that what you have on Argent Vault.
What does Vault have and zkSync doesn't?
There are no guardians as zkSync doesn’t yet support smart contracts, which is what guardians are built on. Which means security features available on Argent Vault such as - recovery with guardians, trusted sessions, wallet locking/unlocking - that are possible thanks to the smart contracts, are not available yet on zkSync.
Should I use Argent Vault instead then?
Each person has a different risk profile and you should define for yourself if guardian features for your crypto activity are worth the higher gas fees you pay on Ethereum mainnet.
One security feature of zkSync is that you can withdraw assets to Ethereum Layer 1 when you want. You cannot be censored on Layer 2.