FuseBase

Initially purchased in 2021 and just added more. One of the best AppSumo buys! The tool offers excellent options, including formatting, attachments, organization, and portals, to name only a few. I use it primarily to document IT how tos and customer data. There are other features I have only dabbled with, and I'm probably only using a fraction of the capabilities, but it is well worth it.
The iPhone app is perfect for on-the-go use.
Customer support is very responsive. Adding my most recent purchase, the storage wasn't showing as increased. My ticket was addressed quickly and resolved.