I've concluded there is no such thing as a perfect holster. Got a box full of "mistakes" that looked good but didn't work well. I finally settled on a Alessi (much like the Galco FBI). It's a high ride that loops on a belt and puts the grip in the right place for comfort. I can walk, run, sit, drive, and lay down without discomfort. I found a change in summer attire was needed though. A t-shirt won't hide it well but a regular shirt not tucked in is fine.
IWBs don't work for me. Too much sweat and discomfort. Can't drive, lay, or sit with a MOB.
What Mikey said, "So, I guess it is a matter of anything you can wear that is comfortable and still allows concealed carry and rapid presentation is what you should look for."
I carry my Colt cocked, locked, and loaded, just as John Browning designed it. My Alessi has a thumb break that adds a margin of safety plus it keeps the gun from falling out when I get active. I would recommend you find one style and stick with it. Should you need to draw the gun, it's nice to instinctly know where it is and how to present it without shooting yourself or a bystander.