Depends on what you want your QR to do? Provide data, URL, your contact info, SMS?
Provide information? I use Kaywa or QRCodePlatform (free) Easy to port to print media.
Lead Capture? Goo.gl or Goomzee or QRCodePlatform Pro.
Under no circumstances do you want to use a QR that is branded with anything other than YOUR data.
Can I attribute any money to the over 12 month deployment of QR....no.
Does indirect data suggest QR has made a difference on some element of business. Yes.