HabitX started from the observation that the streak is doing most of the motivational work in a habit tracker, and that a year-long heat map is a more honest picture of a habit than a percentage is. A month with three gaps in it looks fine as a number and obviously bad as a grid.
You track whatever you are trying to hold onto — exercise, meditation, studying, reading, journaling, eating better — on daily or weekly schedules that can flex rather than demanding a perfect run. Streaks and progress charts sit on top, with smart reminders and a fair bit of customisation for how it all looks.
Shipped in 2019 and still getting updates, which makes it the oldest thing on this page and the one I have learned the most from. It sits at 4.5 stars across 39 ratings, and the reviews are a fairly direct education in where the free tier draws its lines.