It depends on the individual scenario, but from a consumer perspective and dealing with a company for this first time? I would want the protections offered by a credit card purchase. If problems arise with a credit card purchase, you can dispute payments which usually triggers an investigation. I mean you try and do your due diligence with companies, but sometimes stuff happens. I would enter a first time deal with an eye on the worst case scenario, and with cash/check, you are likely on your own.

When dealing with vendors in regulated industries (like generals, electricians, plumbers, attorneys, etc)? You can pursue that angle, most vendors want to protect their license. So if a cash discount is possible, that may be the way to go.