Use stop motion when the job is attention: a brand film, a launch, a conference booth loop, a scroll-stopper on LinkedIn, or an employer-brand piece where the work has to feel human. It is especially strong when your category is visually saturated and every competitor is shipping the same isometric 3D explainer, or when you need an abstract idea - friction, integration, chaos into order - staged as something physical.
Use 2D or 3D when the job is comprehension: explaining a process, walking through a UI, visualising data or hardware. Nobody wants your dashboard rebuilt in clay. Stop motion is also the wrong call if your messaging changes monthly (every change is a reshoot), if you need it next week (fabrication alone will outlast that), or if this is your only video and it has to carry the sales argument - in that case make the explainer first. Stop motion is an attention instrument, not a comprehension one.