IMO since I still have mostly older stuff being broke and all LOL... V3 is pretty workable with most scenes, I like to use The Girl for the gritty/dirty/exciting scenes because she just has the right look for it. As for anime, I stick with Aiko over Maya Doll only because I think she has much more potential.

Granted these are 'my preferences' and they aren't written in stone. Alot of times I may try out a few different figures in a certain scene before making a final decision. It helps to see how the lighting plays on the features you want to focus on especially since there are so many different morphs out there and its lots of fun to see how different each model will look when its done!

So my suggestion is, just try out all of them since you said you have most (or all LOL) of them. With environment it is important to have just the right person in it but remember, you're the artist so you get to personalize it! :D