Make Data Store
Good choice if your leads only need to live inside your Make scenarios: a data store adds or replaces a record by key, comes with your Make plan, and Make's terms include a data processing agreement.
Klozeo fits when a client's status must survive the next run: a data store's overwrite option replaces the record, so you map status and do-not-contact into it, while a Klozeo merge keeps name, status and do-not-contact.