As far as I know CAE and Rishworth are two different companies, perhaps you are referring to the new Resource Group that includes Contractair.
I heard that Sigma is not as good as before, I am using brookfield and so far they are OK.
Certainly it would be nice if some other pilots can share and update their experiences with the most known agencies, quite often the same airline has up to 3 agencies and joining one or another it makes a big difference about the terms and the follow up during the duration of the contract.