Like everyone, I have my own views on accordions and find every choice involves a little compromise. I think double cassotto, 4 voice instruments handle and 'lay-into' the musician better in performance than a 5 voice, but I still prefer the sound options of a 5 voice, especially with musette.

However, ideally I would not choose an instrument over 12kg - but that excludes a lot of otherwise impressive accordions.
I personally don't like having more than 41 keys on PA, but actually think the 45 or 47 key classical instruments look seriously awesome and have a visually pleasing keyboard symmetry. Aparently there are sound musical reasons for the extra keys that are important to the classical artistes. Totally not required for my music though.
Also, I think the big imposing 64 note Bugari and Pigini converter button accordions, like the Nova or Spectrum, look and sound incredible - proper virtuoso instruments, especially in the hands of Hanzhi and others. But actually, for what it's worth, if I had the choice of any chromatic button instruments, I'd still choose an old style Galliano-esque 47 note box with quint converter bass - it's vintage tone as rich and sweet as honey. What can I say... to me Galliano is so tasteful in his musical choices, playing jazz with stradella bass all day long then at the flick of a switch he unleashes the Art of Fugue, just to mix it up...