On social media, the preferred orientation is portrait mode as its the natural screen size as your phone's screen. If you want photos in a digital frame, on TV, etc., you have to shoot in portrait mode. When you mix them, editing them together gets to be a pain in the ass. What do you usually do?
As a professional for over a decade in shooting video and photos ... unless you ONLY want it for TikTok/Instagram ... then go with landscape! There is little that is as frustrating as when a parent sends me video of a kid they want me to use and they've shot it in portrait mode, not only is it annoying to have to edit but for use on television you're killing most of the screen.
Instagram reels are getting really cool and artsy tho. https://www.instagram.com/reel/CcGSLd-DyQP/?igshid=YmMyMTA2M2Y=