I still use V4 (and M4) because there's so much stuff available. Morphs, textures, clothing. Converting is a pain, and often, the results aren't that great. It's easier to just use the figure the items were designed for.

This doesn't mean I don't buy and support other figures. But it's hard to compete with the huge backlog of stuff created for V4. Paid and free. (It doesn't hurt that V4 stuff is often super cheap these days.)

I still use V3 as well. There isn't as much stuff currently available for her, because she was supplanted by V4, but I have a  big V3 catalog, because I was here when she was new.

For some reason, I find the Gen 3 figures the best for getting a likeness. I think there are more polys in their faces. Or they are better arranged or something.

That's something I find disappointing about the newer figures. They all have a certain blandness, that's hard to morph out of them. At least with my (very limited) skills. Maybe a result of relying on subdivision? The kind of characters available for, say, La Femme, is still extremely limited, years after she debuted.

I do have high hopes for Dawn 2. But even if she's a mega-success, it will take YEARS before she has as much support as V4.