I have been working in Cyprus for many years. I think the best approach is to look for someone who has the rates and service level you would like. Sometimes the best for one client is not the best for the next client. Also, a different client might be happy to pay 300.000 on fees because they heavily rely on the provider whereas the next client is not.
Aside from the fees, ask from you provider, whoever they are to provide references. References from the client.
The simplest test which I apply is usually the corporate website. From the website of the group, if you don't see any real people faces and any real names I would stay away from them, they are sneaking around, trying to hide in the cracks.
Cyprus is becoming very transparent and it has lost its appeal to certain structures while other structures have fallen in favour.