Good question! I do use all three frequently, but carry the Constance the most, even though I believe the Verrou is the more practical of the three...

So thinking aloud why, I think it is down to color and leather. I don’t love Epsom and even though Indigo is a wonderful color it lacks depth in that leather so it is not quite the black substitute I had hoped for. Still, love that bag, it is so well thought out and practical.
The Celine classic is a a recent addition and it is natural leather so I am perhaps still a bit too careful with it. It is going to be more of a Summer bag for me.
The Constance I have had for a long time. The leather is chèvre coromandel and just so beautiful and easy. I think of it more as a Winter bag but the fact is it goes with lots of my clothes (I love blue and brown together) and I wear it all the time. I love the brushed palladium too, I used to have a Constance with gold hw too but never wore it.