I have a relatively busy life with many areas of concern and a poor memory, so I rely heavily on notes to document and remember things.
Offline: No Editor implementation: Web/Electron Mobile exp: ★★☆☆☆ Sync: N/A Org: Hierarchical
I used to use Notion. Notion is organized around the idea of content blocks. Each block has a type; text, image, database etc.
Databases are probably the most distinguishing feature of Notion. They're an in-app implementation of a hybrid between a spreadsheet and a relational database. The nice thing about databases is that you can choose their display formats; for example, a database with a date column can be displayed as a calendar.
Notion's biggest strengths are databases and the ability to embed any type of content inline - images, pdfs, maps, calendars etc. It's got a very rich presentation and you can make some truly beautiful and functional notes with it. Databases are very powerful IF you are the type of person that is willing to spend large amounts of time curating structure for your notes.
My biggest issues with Notion are, in order:
Offline: Yes Editor implementation: Web/Electron Mobile exp: N/A Sync: Yes Org: Sequential
Logseq is interesting. It's an outliner with a unique model for note taking. It's organized around the idea of a sequence of logs. The happy path for logseq is that each day you open up today's daily note, write whatever it is you are working on or thinking of, and attach identifiers to blocks of content. Later on, if you want to extend the notes you took on that content, you're supposed to synthesize a new note in today's journal page by transcluding the content you already wrote via its identifier. Then there's some hand wavey idea that “later” you'll pull all of those blocks into their own topic pages.
This probably works for some people but it's way too much effort writing notes to be useful for me.
Offline: Yes Editor implementation: Web/Electron Mobile exp: ★★☆☆☆ Sync: Yes Org: Hierarchical
Currently I use Obsidian. Obsidian is fundamentally a markdown editor. Then it has a whole host of plugins that add rich presentation and other capabilities into the markdown editor.
The editor itself is pretty nice. If you've used electron apps before you know that sometimes they feel native (e.g. Discord) and sometimes they feel like a webpage running in Electron (e.g. Logseq, most others). Obsidian's editor feels very native.
Markdown as a content format is both a blessing and a curse. On the one hand, all user content is plain text. That has many advantages - easy to get at your content, easy to exit the ecosystem (in theory), syncing is fast, on disk size is light.
On the other hand, Obsidian wants to have its cake and eat it too. It wants to get all the advantages of Markdown but also offer high level functionality such as task tracking, tabular data storage, query languages etc. To make these work well, the underlying data really wants to be structured. But there is no structured data store in Obsidian, the data format is “just Markdown”. How to solve this conundrum? Most of the value-added features do so by storing structured data in Markdown. This is such an obviously bad idea and the results are as bad as you might expect. You end up with a bunch of shitty home grown databases whose disk format is an insane extension of Markdown. Now it's no longer easy to exit the ecosystem, you cannot get at your data without the Obsidian code necessary to render it, etc.
Consequently I don't use any of the plugins in Obsidian that do this and so for me, most of the advanced workflows are lost on me and it ends up as a glorified Markdown editor. However, the editor itself is quite nice so it's still worthwhile to use it vs e.g. vim on a directory tree. The sync service (which costs money) works well and does a good job syncing apps between my various computers and phone. The mobile editor is not great but as it is an App it's more functional than alternatives. Writing Markdown is fine when you have a full keyboard but it's not a good experience on mobile.