I have finally tried Obsidian and can say it truly is the best app. Why: It works wonderfully on all platforms. Fast and snappy. It's closed-source, but uses Markdown, which is universal and forever will be supported by computers, you will never loose your notes, nor need to convert them. Lots of community plugins. Like Excalidraw, which is a god-like tool for taking handwritten notes. Great customizability. Your notes get automatically synchronized for free through iCloud or OneDrive. Everything is stored on your device/cloud, so no waiting for the database to load, no downtime, and easy backups, you own your notes. Supports LaTeX so you can type math equations straight into your notes, you can also use snippets plugin to speed-up your note-taking, snippets are useful for everything, but for Maths and Engineering the most. Do you see any downsides to this app? I went through almost every solution, starting with Evernote back in 2015, and this one finally I really love.