Three tools, three philosophies. I use all three (or have used them extensively), and I'll be as honest as I can about where each wins and where it falls short.

Where it wins: Team collaboration, database views, and the block editor. Notion's ability to combine text, tables, kanban boards, and databases in a single document is genuinely good. For teams that need shared workspaces with structured data, it's still the default choice for a reason.

Where it falls short: Your data lives in Notion's cloud. There's no self-hosting, no standard export format that preserves relationships, and no way to connect an AI of your choice. The AI features are Notion's own, locked to their provider. If you want to switch tools, you lose the structure — the markdown export strips relationships, rollups, and most metadata.

Best for: Teams that prioritize collaboration and don't mind vendor dependency.

Where it wins: Local files, plugin ecosystem, and true ownership. Your notes are markdown files on your disk. You can open them in any editor. The community plugins extend functionality dramatically. If you value ownership and extensibility above all else, Obsidian delivers.

Where it falls short: Everything is a document. There's no structured entity system — a "task" is just a line in a markdown file with a checkbox, not a typed data object with properties. Linking is manual (you have to explicitly [[link]] things). There's no AI-powered organization, no semantic search out of the box, and collaboration requires a paid sync service. The barrier to getting value is high — you need to build your own system.

Best for: Individual power users who enjoy building systems and want full local control.

Where it wins: AI-driven organization, data sovereignty, and the entity model. You capture messy input, AI structures it into typed entities with properties and relationships. Your data lives on your own PostgreSQL server, not in a shared cloud. Any AI model connects through an open protocol. 12+ view types render the same data in different shapes. The proposal system keeps AI transparent and controllable.

Where it falls short: It's newer. The ecosystem is smaller than Notion or Obsidian. Team collaboration is Phase 2 (currently single-user focused). The desktop app is Electron-based, which some users find heavier than native apps. And the concept of "entities + views" takes a moment to grasp if you're coming from a document-centric tool.

Best for: People who want AI to handle organization, want to own their data on a real server, and want to use any AI model — current or future.

The choice comes down to what you value most:

If you value team collaboration today: Notion.

If you value local files and DIY systems: Obsidian.

If you value AI-powered organization + data sovereignty + model freedom: Synap.

These aren't the same product with different branding. They represent different beliefs about how knowledge should be stored, organized, and accessed. Pick the one whose philosophy matches yours.