[alexu]

REST, because of forward and backward compatibility

SOAP is too strongly typed for most startups. Most likely you will be changing your API quite a bit over next few years and with REST for each new version of your API you have option of

1. Create new entry point (new URL)

2. Specify version in the HTTP headers

3. Expand request/response spec with new elements

Because most SOAP libraries implement very strong binding to WSDL schema you will be forced to create new entry point for every version of your service. FedEx learning this hard way right now. They moved their API from REST to SOAP and they have no clue how to update it now without breaking all the developers.