I have been looking at the Google Cloud Endpoints which is Googles Rest API offering. The big thing is what it offers right out of the box.
1. SDK for Cloud Endpoint development (AppEngine)
2. Backend Services support for OAuth 2.0 Authentication
3. API Explorer
Languages support is Java, Python, PHP and GO.
Hosted on the Cloud, monitored on the Cloud, the Google Cloud that is. Different types of models, Multi Tenant or VM.
Pricing Calculator Available.