Since REST is the de facto standard, you should use REST services unless there is a compelling reason not to.
App services are a user friendly way to use SOAP services. You should not use app services, unless:
- You are a citizen developer and the complexity of REST / SOAP puts you off
- You will never reuse this integration for anything else than Mendix
Please just use REST instead of app-services.
Appservices, in my opinion, are an attempt at making their own integration standard that nobody actually uses.
Thanks for the advice.
My experience is that App Services takes really more time in developing, integrating (publishing in the company app store with different versions etc) and maintaining it over several apps and versions.
While the API integration and maintenance is less time consuming and more transparent to do self.