My company has a PHP website app. And we are now thinking about building the integration with Salesforce. So based on my understanding, we would build an app in app exchange to integrate with the PHP app, which consists of several triggers, custom objects and a few VF pages and tabs. And the package will probably expand in the future.
My question is in this case, which kind of org should we be using? Traditional Production/Sandbox structure doesn't seem to suit in this case because we are just developing an app for our customers. Developer edition seems to be very attractive to me since it is free. But I am not sure whether there will be issues with it. Another option is using TSO/ISVforce orgs. It seems to be the default option for a company to develop apps on App Exchange. And becoming an ISV partner can raise cases for Salesforce support which will probably be needed in the future. But I can't think of other benefits aside from it.