The reason most people use Mike and Vicky is the same reason most people use Windows and not Linux. It's what everyone else uses, and that's very convenient.

I never had much use for Don and Judy. It takes a lot of work to get them looking decent. I do like the way their morph dials are set up, organized so that you don't have a whole long list at the same time. But other than that, they have no appeal to me. Maybe if the Face Room worked as advertised...but it doesn't.

I actually prefer Stephanie Petite and David to V3 and M3, but there's so much more stuff available for V3 and M3 that I use them more. And that's probably what it comes down to: there's tons of stuff available for DAZ's figures, and almost nothing for Don and Judy.

If you want to try a different figure, there are free ones. Mayadoll is free, and has a fair amount of stuff. Sixus1 also offers several free figures: Lilin, Adam, the Behemoth.

Actually, I think that's the only way you can even make a dent in DAZ's monopoly: give the figure away free, and hope people like it and start making stuff for it.