Best second brain tool for solo founders

There are roughly 40-60 legitimate competitors in the 'second brain' space (Obsidian, Roam, LogSeq, Notion, Tana, Mem, Plasticity, etc.), but most are either too complex for solo operators or too generic to solve founder-specific problems. The common failure pattern is feature bloat—these tools optimize for power users and networked thinking, but solo founders are juggling product, marketing, hiring, and fundraising simultaneously. They don't need another playground; they need fast capture, quick retrieval, and decision-making support. The actual gap isn't in note-taking itself; it's in tools that bridge the gap between *capture* (what you learned) and *execution* (what you're building next). An opportunity lives in building for the exact founder workflow: quick voice notes that auto-tag, integrated task-to-learning connections, and AI that surfaces relevant past decisions when you're stuck. The winner here won't be the tool with the prettiest graph view—it'll be the one that saves a solo founder 5-7 hours a week by reducing context-switching and enabling faster decisions.