My gut feel is that document based web services are preferred in practice - is this other peoples experience? Are they easier to support? (I noted that SharePoint uses Any f
BiranLy's answer is excellent. I would just like to add that document-vs-RPC can come down to implementation issues as well. We have found Microsoft to be Document-preferring, while our Java-based libraries were RPC-based. Whatever you choose, make sure you know what other potential clients will assume as well.