After much discussion and votes and new logo and icon for Joplin has finally been decided:
In the end, it is an icon relatively similar to the previous one but with a unique style for the "J", which gives it a distinctive look.
Perhaps that's the best way - evolving and cleaning up the icon rather than radically changing it. Another advantage of this icon is that it does not represent any specific object (it's not a note, or notebook), so it does not restrict the scope of the project, which as it grows, is becoming more than just a tool to take notes.
Finally, this icon scales well at different sizes, including down to 16x16 pixels which we need for tray icons. It also works well inside circles (for Android) and square shapes.
Over the next few weeks, the icon and logo will be updated in the various apps and websites. That will give an opportunity to refresh the icons used throughout the apps, as several of them have incorrect dimensions, in particular on desktop and Android.
For information, this was the final tally, with Patreon and forum votes combined, with more weight (2 points) given to the first choice:
A 30
B 45
C 115
D 135
E 61
Many thanks to everyone who's contributed to the votes and discussion!