If the Android Github app were updated such that the Gist support was a little richer for things like Markdown and those checkboxes, then I really think this might be the best.
The hardest bit I have with todo lists is keeping them current and accessible, meaning syncing across all devices and work-stations/laptops. Git is perfect for this, and this use of Github Flavored Markdown is pretty neat... the only missing thing is a mobile way to manage them efficiently.
I've also found that the gist support on Android GitHub is poor. Hopefully this will improve in the future. The nice thing about GitHub is that they listen to feedback. Most likely someone there is reading these comments.
Also, come on people, you all know that "Best" is subjective. This is the best tool for this guy, so there's no need to shoot it down.