Well I started on VBA macro-enabled Excel files several several years ago. Then, I learned that you could create a text file with extension .vbs to perform those same actions but with slightly different syntax. Then, I just explored vb.net while using UiPath and learned some of the useful functions that help create efficient automation.
One thing to understand is that if you know it can be done, then you can look up how to do it.
I don’t know if you can really only learn one while not learning the other, since they are all pretty much the same with just slight differences, but I think the most useful skill is vbscript in general because you can run these scripts external from the application that it automates. Learning some LINQ tricks are also useful for using in UiPath.
EDIT: Easiest way to learn VB though is when you can see the functions listed out, so maybe VB or vb.net is better