out of all of my tools, my favorite is one of the least popular: hk.
IMO it's the most innovative one and I still haven't seen anyone try to replicate what I'm doing in it. (Specifically I'm referring to the deep integration with linters/formatters). Every other tool (save for maybe pitchfork which also isn't that popular) has loads of competition from similarly great tools.
Ironically, I think this is also why it doesn't get as much attention as my other projects. If something is too innovative, it's too different, and therefore challenging to convey the value prop.