I'm somewhat surprised that 44 comments in, it looks like I'm the first to mention Roam: https://roamresearch.com/
It obviously wasn't the first note taking app, and it's very much not Free, but the nature of its linking sparked Obsidian and Logseq's growth. I've been a happy paid user since the early days.
The biggest reason I stick with it is that it supports both being E2E encrypted and synchronising, without me having to set anything up. I wouldn't mind running a server, but (unlike many in the comments) I actively don't want my tool to operate on a pile of Markdown documents on the filesystem: because then I need to worry about maintaining those files everywhere I want to access my notes. Roam will automagically drop an encrypted backup on my laptop every day, my regular backup system will take things from there. For day-to-day use, sync is per-block and effectively live.
It obviously wasn't the first note taking app, and it's very much not Free, but the nature of its linking sparked Obsidian and Logseq's growth. I've been a happy paid user since the early days.
The biggest reason I stick with it is that it supports both being E2E encrypted and synchronising, without me having to set anything up. I wouldn't mind running a server, but (unlike many in the comments) I actively don't want my tool to operate on a pile of Markdown documents on the filesystem: because then I need to worry about maintaining those files everywhere I want to access my notes. Roam will automagically drop an encrypted backup on my laptop every day, my regular backup system will take things from there. For day-to-day use, sync is per-block and effectively live.