Landlord Referencing for Tenants

What is the best landlord referencing sites out there covering Full Tenant Checks to include affordability, employment/earnings verification etc. that would also be suitable for Rent Guarantee Insurance?

OpenRent has a sample document that states they use "RentGuard" but what I don't understand is why would anyone pay £20 for basic when they offer the comprehensive service for the same price? Some reviews out there state that the reports aren't from RentGuard - can anyone confirm?

What about RLA Tenant Referencing? I am trying to source a sample report but no luck yet.

I have also found that "Total Tenant Referencing" uses Rent4Sure - anyone used them?