if you want awesome flight performance, use betaflight
there is also a slightly more robust autopilot firmware, dronin (which is an openpilot continuation) which can run on the flight controller listed on that blog post: https://github.com/d-ronin/dronin/issues/9
then for firmware, there are 3 modern forks of multiwii: cleanflight, betaflight and inav.
if you want gps navigation, put iNav on it: https://github.com/iNavFlight/inav/
if you want awesome flight performance, use betaflight
there is also a slightly more robust autopilot firmware, dronin (which is an openpilot continuation) which can run on the flight controller listed on that blog post: https://github.com/d-ronin/dronin/issues/9
full disclosure, that's my blog :)