How many fertility apps?

Hey ladies! Just curious.. How many fertility apps do you follow? At first I used Life. But then I came across glow as I was browsing through App Store. Started using glow since July. I use Ovia too because I saw many women mentioning it here. But what bothers me a bit is, each app shows a different ovulation date, even though I enter the same data in all the apps.. Should I cut back and just use glow? Help me...