Either one, you're going to need to have some idea what you're doing. Basic setup has fairly easy to use "wizard" type processes but anything complicated (e.g. setting up IPSEC or OpenVPN) you're generally presented with a large page of options and so need to understand the basics. They both have a level of help for each option built into the page - I'd consider them fairly equal in that respect.

Also if you are using opnSense and need help, don't ignore the pfSense forums. They've been around a lot longer and there's still a lot of good information in there which can be useful for getting a particular setting right. Because of course the underlying applications and OS are all basically the same, the same options will apply. The opnSense forums are still useful though (they just don't have the history) and I can almost guarantee you'll get a nicer response there.