To be honest, I use two figures primarily. One is V4 (the Non-weightmapped version). And that's mainly because I have a lot of stuff for her. Plus I use her as an on-going character in a webcomic that I do.

The other figure is Alyson2. Mainly because I just like her, and she's weightmapped for use in Poser.

I have no problems with using other figures, including Mariko, but I also have no overwhelming incentive to use her.