It's closer to Quickbooks. Gnucash's interface is stripped-down but fairly friendly, focused directly on the chart of accounts and registers, with lots of keyboard shortcuts and relatively little unintuitive behavior. It runs fine for me on MacOS 10.14; the developers keep it quite up to date. It's very powerful and I believe you could run nearly any SMB on it, much less personal finances. That said, I haven't touched QB in a minute, and never their online offering, so I'd love to hear how it compares from somebody who's used both.
(Not specifically to parent:) You will need to know double-entry bookkeeping to use Gnucash. While there is no in-app tutorial and little hand-holding (by default the "Debit" and "Credit" columns of the register are given friendly names), there is an excellent Tutorials and Concepts guide https://gnucash.org/viewdoc.phtml?rev=4&lang=C&doc=guide that starts from first principles on basic accounting, and has tons of examples of how to enter various transactions. I was very impressed going through it, as a layman; it's a hidden gem and better than 90% of the "accounting tutorial" websites out there.
(Not specifically to parent:) You will need to know double-entry bookkeeping to use Gnucash. While there is no in-app tutorial and little hand-holding (by default the "Debit" and "Credit" columns of the register are given friendly names), there is an excellent Tutorials and Concepts guide https://gnucash.org/viewdoc.phtml?rev=4&lang=C&doc=guide that starts from first principles on basic accounting, and has tons of examples of how to enter various transactions. I was very impressed going through it, as a layman; it's a hidden gem and better than 90% of the "accounting tutorial" websites out there.