More on Amapi: Amapi Pro went to eFrontier (which is now Smith Micro). Not sure if Amapi Pro 7.5 is there, still.

Amapi Pro is more focused on Nurbs modeling. A bit like a Rhino alternative

Another product, also focused on modeling, and also from the developers who did Amapi (and Carrara), is HExagon.

And, you'll find a number of tools from AMapi in Carrara pro, in its vertex modeler,

That is in fact one whing you might want to consider: the vertex modeler of Carrara. www.thebest3d.com/carrara for older versions. Or go with Carrara 6 or better yet Carrara 6 Pro - if you're a Platinum ember at DAZ it's really cheap