I use vim cause it lets me stay on the home row with my fingers and it flies when you're used to it.
So I use vim-wiki cause it lets me switch between coding, notes and my todo list without leaving vim, the terminal, it taking my fingers off the keyboard.

Just a friendly hint: If you plan on making this a commercial product and earning money with it, be aware that the people here are a tiny niche, and probably not the type of people who will pay money for software as a service.