You know I was gonna ask the same thing a few days ago but you beat me to it [LOL].
At the moment for me I pick the figure to use to go with the scene, I'll explain a bit more. I have a scene in my head and the type of clothing the character needs for that scene, so then it comes down to which figure I have that clothing item for so at the moment I still use V3 heavily simply because I have loads of stuff for her for most situations.

I can't say the same yet for Sydney, V4, Jessie G2, Miki G2 etc. etc. [LOL].

So that's how I do it!!

Injustice will be avenged.
Cofiwch Dryweryn.