Yes, I have heard of folks that have issues with SCCM and it is not a popular tool to use in patching SQL Server. WSUS acts a little different than the Windows Update agent on a server/desktop. WSUS gets a list of all patches available after they are released from Microsoft. There is a sync task that is used to "sync" your WSUS server with Microsoft servers for the patches that are available and shown needed within your servers/desktops.
I suppose it becomes a matter of personal preference. I'll definitely check out WSUS to see what it has to offer, but it sounds like another tool we'd need to administer, whereas the batch files or powershell scripts are items we can have full control over without really having to rely on agents or tooling to roll out the updates.
Best Regards,
Steve