We can talk about 1000 holsters and have as many varied opinions about them. This is from personal experience and force on force with sims and real people.
Kydex is fast, leather is slower, owb is faster and iwb is slower. The fact is that what you gain in speed deters from retention and the more retention we have the slower we are. So we need to find a happy medium for the CCW and I admit it just will not work for everyone. The Leather IWB is best for concealed carry. In numerous FOF scenarios nearly anyone that had a plastic or kydex holster, especially an OWB lost there guns to the bad guy or ended up fighting over the gun. The kydex being fast offered the easy opportunity to slide the gun out, the plastic holsters like Fobus usually burst at the rivet points and became totally separated dropping the gun. That’s bad jo jo there.
The leather iwb fits inside the pants and the leather being able to collapse slightly under body and belt pressure add good retention and still be drawn under 1.5 seconds with practice.
I do use kydex and use it frequently in IDPA, classes and inthe winter when the gun can be hidden easier. So no I am not knocking any of them, just remember that faster may not always be better.