CRM that integrates with Zoho Books

We are currently using Zoho CRM but we're finding it too complex, cluttered, and not very intuitive. We also want to utilise a CRM so that it captures both sales potentials/customers, as well as partnership contacts and other non-customers. This will make it easier for us to export contacts for email newsletters. However, we are happy with Zoho Books and don't want to delete all existing accounts and invoices. Can anyone recommend a CRM that integrates well with Zoho Books?