I don't know about the other two, but the Sonnet is very easy to maintain (if that criteria is important to you). I have the cheaper version (aluminium body with gold trim), the nib and feed easily comes out with a pull. The nib is attached to the feed via a pair of tabs on each side of the feed. Once you have that disassembled, washing/cleaning/drying the pen is a breeze.
Thanks... Yes maintenance matters. It all matters; writing smoothness, line, ink flow feel-grip, build quality and styling.
Strangely, I had made up my mind to get the Sonnet (the one pictured). Then it was gone. I lost my chance for the one I wanted at the price I could pay.
So I wound up with my second choice.
A deep brown Waterman Expert with palladium trim.
We will see...