My 2 cents, FWIW...
IWB vs OWB vs pocket, leather vs kydex, hip vs appendix...it all comes down to personal preference.
I find IWB
more comfortable than OWB because when I've carried OWB it always felt like the gun was pulling away from me. And before you ask, it was a good quality holster/belt combo. Plus, I don't have to worry about my untucked shirt riding up and exposing the holster. I also don't have to re-size my pants' waists for IWB, though I do have to make sure my belt will accomodate it.
I've also worn both kydex and leather IWB. Even though kydex is thinner, it wasn't as comfortable as leather. It was still comfortable to wear, just not as comfortable. I think leather is a little more conforming to one's body shape.
I've never tried appendix carry, but have considered it. There are pros and cons, but between my, um, "tactical waist padding"

and my habituation to carrrying a gun behind my strongside hip, I decided it's not for me at this time, but I'm open to re-evaluating and changing my mind later on.
I rarely pocket carry, and what I've found is that it's only faster than belt carry
if you already have your hand on your gun in your pocket*. I can draw faster from my IWB holster, concealed under an untucked shirt, than from a pocket holster, if my hands are outside my pockets. It's also more difficult to draw from a seated position or while on the move if the situation dictates either of those options. So you should weigh accessibility/speed vs concealment.
But all this is what I've found for me, based on my experience and training. Different people have different needs/wants, so ultimately you'll have to do some experimenting to figure out what's best for you, or just stick as close as possible to what you're already familiar and comfortable with. There's nothing wrong with either approach.
* Stop snickering.