I play around a little making my own instruments. I wouldn't say I'm a good luthier, or that I know a great deal. I am also exclusively a fingerpicker. I think that , everybody's perception of the sound and playability that they want is personal to them. I have however noticed that smaller bodied guitars seem to be more responsive to finger picking. Sometimes 12 fret to the body guitars are more responsive.
I have quite big fingers. I have noticed that a wider string spacing or neck, particularly up near where you strike the strings allows me to play with my whole finger rather than just my nails. I think that this allows me to vary the tone more and save my nails.