I think it's really dependent on each individual person, and their activity level. I have several nice open top holsters, and I use them, and I like them, but they primarily get used when I am very certain I'm just going to be walking around the house, or in the truck, etc.
Mostly I favor a thumb snap, I'm outdoors a lot and around the farm a lot and don't wanna be worried about my gun flopping on the ground all the time.