They are not really comparable, IMO. Yuki is an anime-style figure. Miki is more realistic. I suppose that makes Yuki "cuter."

I don't think either of them share textures with any other figures. Miki is mapped sort of like James, I believe, but not entirely.

Neither of them comes with much in the way of morphs. Miki has head and body morph packs for sale at RDNA, as well clothing and textures. Yuki has been completely re-done. Yuki 2 is rigged differently than Yuki 1, so I suspect the clothing made for her will have to be re-done as well. There was never much to begin with.

I think Miki is going to be more successful than Yuki, simply because she fills an empty niche: realistic Asian woman. Vicky does not do ethnic very well, so people who want realistic ethnic characters love Miki and Koji.

Yuki is cute, but she has a lot of competition: Aiko, Mayadoll, etc. She really doesn't let you do anything you can't do with A3.