Which video-editing-related skill should I learn next?

I was a graphic designer for print media in the past, but I am now a full-time freelance video editor. I mostly use Premiere Pro in my current work, but I want to expand my skill and hopefully the opportunities (for more $) too.

I've been contemplating for days whether to learn motion graphics, 3D animation, or UI/UX. I have a bit of knowledge in all of those, but I want to focus on just 1 and try to master it.

Any advice/opinion shall be greatly appreciated!