I owned both devices.
- In my personal opinion the Inkpad 3 is more comfortable to hold than the Aura One.
- You can of course add your own fonts to the Inkpad.
- It is true, there are not so much tweaks and patches for the Inkpad. That is, because you don't need them
Many issues with the Kobo Aura don't exist on the Inkpad. Adding third party software as KOReader or Cool Reader is no problem.
- The comfort light is more uniform, light is easier to adjust.
- The library system of the Inkpad is much better than on any other ereader I know.
Both devices have there pros and cons. In the end it's just a matter of your own preferences, I guess.
BOT, I love page turn buttons on an ereader, but I don't ike the wedge-like design on the Forma. I also find the Forma quite pricey. In that price category I would prefer to buy a Kindle Oasis. Actually that's what I did, but I love my Kobo devices just as well.