The short version: vertical (9:16) is built for phones and dominates Instagram, TikTok and Facebook Reels. Horizontal (16:9) is built for screens and still leads on YouTube, websites and, mostly, LinkedIn. The honest answer for most businesses is that they need both, which is why every job we shoot gets planned around the platforms it's actually going to. Framing a shot for both formats from the start is far cheaper than reshooting later.