Smaller is better.
Here in WA I can legally carry, but I don't very often because I actually feel safe most places around here. But I've tried it, just because you know, rights have a way of disappearing if you don't exercise them.
Well, what I learned is that most guns are just too damn big and heavy. Even guns you think of as smaller, are pretty big and heavy when they are stuck in your waistband. I put my P320 X-Compact (3.6" in barrel) in an IWB holster and tried to get through the day. It's a pretty small gun, but it still manged to jab itself into my rib cage when I tried to sit in a car seat, and it was always sticking into me in uncomfortable ways even just sitting in a regular chair, you kind of have to position yourself so you're not sitting on it or it's pretty uncomfortable. I had it IWB at around 4-5 o'clock. I thought about appendix carry but couldn't quite bring myself to point a loaded gun at the crown jewels.
Walking around with it was better, but it did do a good job of making my pants sag even with a thick gun belt on and even though it's a plastic frame.
If I were really going to carry every day I'd get the smallest gun I could actually shoot. Maybe a P365, or one of the smallest glocks. Something people think of as a pocket gun, but I'd put it in a comfortable IWB holster of some kind.
People worry a lot about printing, but actually your first concern should be comfort, otherwise you won't actually carry it.
Also I think 10 vs 15 rounds is a red herring. Most civilian involved shootings are over in under 6 shots as I undestand it, 10 is already more than you need, and you could carry an extra mag if you were worried about it. Presumably if you really fire off 10 shots you're going to be able to find a moment to reload, and if 10 aren't enough, 15 probably aren't either--so you'll need that extra mag. In other words, I'd be fine with the "limited" capacity of the P365 or whatever the smallest glock is.