What makes you stick with an app?

I used so many different apps over the years trying to manage my time or tasks or help with motivation. Once novelty factor wears off most of them start feeling like a chore. I hate streaks in apps and notifications (with some exceptions), so the only apps that I keep using are the ones that somehow fit into my system or way of thinking.

I know there are plenty of threads discussing and reviewing apps, but I'm not asking for any specific recommendation - rather I'd like to hear what makes an app "work" for you?