What key factors should I consider when choosing CAD conversion services?

I’m looking into CAD conversion services and would like to hear from people who have experience with them. If you’ve ever converted scanned drawings, old paper plans, or PDF files into editable CAD files, what factors did you consider when choosing a service provider? I’m particularly interested in drawing accuracy, turnaround time, pricing, and overall reliability. Is there anything you would recommend checking before making a decision?