Hard Materials
> Ceramics
> Wood
> 3D Printed Hard Plastic (PLA/ABS)
> Injection Molded Hard Plastic
Soft Materials
> Natural Fabrics (Cotton, Silk, Wool)
> Synthetic Fabrics (Vinyl, Polyester, Nylon)
> Fur/Hair (presumably synthetic, inb4 yiff in hell)
> Silicone or TPE Rubber (TPE is basically a cheaper form of silicone)
I'm strongly biased against the hard materials for comfort reasons. Personally, I have a hard time seeing myself falling in love with something hard, but others on this board talk about using hard materials, so I'm trying to keep an open mind.
My preference is for silicone, but there are four big problems with it. Firstly, it's expensive. Secondly, it impedes modification after the silicone has set. Thirdly, it contributes to the uncanny valley/silicone slut issue. Fourthly, it is heavy, and this weight really constrains the skeleton, posablity, and probably robotics. Because of the weight, silicone dolls have heavy-duty skeletons.
My second choice is therefore fabric, presumably stuffed with cotton. Fabric is super comfy, and has no uncanny valley issue. A non-fuggable fabric doll or robot would have no stigma issue, and could be the start of a productive hobbyist scene with plenty of females. Fabric is extremely lightweight which could be a plus or a minus. By itself, its unsubstantial and not ideal for robotics. A fabric robot is possible, but it requires hard, heavy parts underneath to provide structure and as actuators, which would make it less comfy. The fabric could be a textile (cotton), a synthetic leather (resembles skin, makeup/dress-up potential), or synthetic fur for you furfags out there.
Another possibility is a hard vinyl BJD-like doll with a layer of something comfy on top. Alternately, you all can reject my comfort autism if the benefits of having a hard doll/robot are clear enough. I'd like to hear others make the case for a hard doll/robot, since I don't think I could do the argument justice.
Finally, this is a discussion, not a debate. There are multiple paths we could take, and I'm sure different robowaifuists will try different techniques to see what works and what doesn't. I'm more interested in seeing what options are on the table than shutting down any particular approach.