98% of the time its OWB with a tight fitting pancake holster. While you can get a touch more concealment out of the IWB I think its a bit of a trade off.
I have practiced a fair amount but not a ton from IWB and I cant present nearly as fast or confidently from IWB. Getting my thumb between me and the gun and burying the web of my hand is not nearly as smooth or as natural.
From OWB I can always pull up and naturally be on target .. I cant say the same with IWB.
More practice would probably solve that but since I dont have to go to a job every day and we live in a state where I dont have to deep conceal I will stick with a light shirt over my gun OWB. the shirt helps keep the sun off my skin anyway.
Comfort wise IWB especially if its plastic will start annoying me fairly quickly.