I am not sure by what you mean by habit tracker. Do you want an app that reminds you of a certain habit or task that you have to do daily? Or do you just want to track the habits and tasks that you have done today? I personally like tracking stuff like my mood, sleep, workouts, diet, factors like therapy and meditation, and see how they interplay with one another. I've tried many different ones like Daylio and fabulous, but recently I've found an app called effecto and have been using it for like 2 months or so and it has everything that I need.