What's Your Web Service Protocol Of Choice?

    I have been doing a lot of web service development at work lately. I completed a FedEx integration for WorkXpress and have been working on a new integration with Drupal. Each of these integrations have involved using both SOAP servers and clients (the client being WorkXpress).

    This has led me on a quest to learn more about web services. While I'm experienced with SOAP and WSDL, I really don't know much about the underlying architecture. I also know very little about other web service protocols (such as REST and XML-RPC). I found a really good article at http://michaeldehaan.net/2008/07/17/xmlrpc-vs-rest-vs-soap-vs-all-your-rpc-options/ which highlights the pros and cons of different protocols.

    Having read all this, I'm still not sure what the current preference is. Specifically with web developers, but I would like to hear from everyone. So, what's your web service protocol of choice?