Monday demands a serious setup effort before it becomes reliable for your team. Most people sign up, invite a few teammates, and then abandon it because getting processes mapped and documented in Monday is a pain unless you bring in a consultant. If you're not up for that kind of lift, Monday just turns into another unused tool.
Shortcut's main issue is that it's built on a decade-old, legacy tech stack with a reputation problem from its Clubhouse days. It doesn't offer the kind of modern experience you'd expect in a project management tool, and the underlying tech debt makes it feel dated.
If you care about having a tool that can actually work for your team without feeling ancient, Monday is the better pick, only if you're willing to invest the time and energy into a real implementation. If you want something modern and usable out of the box, neither is a slam dunk, but Shortcut falls flat for anyone who expects up-to-date tech or a fresh interface. Monday is the only one here that can be made to work, but expect a heavy lift.