The question isn't "2D or 3D". It's "what does this piece need to tell". Many animation decisions are made backwards: technique first, message second. It's an expensive mistake, and it shows in the final result long before it shows in the budget.
2D excels at abstraction, rhythm, conceptual transitions, editorial motion graphics and campaigns with a fresh or illustrative tone. 3D shines in product, space, physical light, multi-campaign brand continuity and anything where the viewer needs to recognise a real object. Mixing the two is, today, the most interesting approach in many campaigns; but the mix has to be driven by the script, not by the studio's portfolio.
Message first, technique second. Do it the other way round and you fall in love with a process that doesn't solve the problem.
When 2D is the right choice
When the piece has to explain an abstract concept: a software feature, a financial service, a brand idea. When the budget demands quick iterations. When the brand has a defined illustrative universe and the animation has to extend it, not compete with it. And when the tone sought is close, editorial or relaxed.
When 3D is the right choice
When there's a real product to show and photography falls short: internal details, exploded views, finishes that require light controlled to the millimetre. When there's an architectural space that doesn't yet exist physically. When the campaign will produce 10, 20 or 50 pieces over 18 months and we need a reusable pipeline. When the brand demands strict visual fidelity to its identity system at any angle and light.
When to combine 2D and 3D
Explanatory branded content where the product is the protagonist but the message is conceptual. Animated spec sheets. Long spots with graphic headers and a "real" body. Editorial motion graphics over real or rendered plates. Here the mix generates rhythm, holds attention and avoids the "tech demo" effect that appears when a piece stays purely in 3D.
The decisions made before animating
Colour system, typographic library, brand motion principles, virtual-camera rules if there's 3D, piece length and narrative cadence. All of it is decided in pre-production, not in the animation session. When it's decided late, every shot change costs days of rework.
What we learned doing a lot of both
That the best animation is rarely the most technically virtuosic. It's the one most aligned with the message. That good 2D can have the presence of 3D if the storyboard is well crafted. And that badly directed 3D is just an expensive render no one will remember.
