I have used OWB holster almost exclusively for years now, as I find them WAY more comfortable, most IWB holsters have no retention strap, which gives me the willies, persoanlly (YMMV), and I find a gun in an OWB holster is, for me, WAY faster and easier to access, even when it,s concealed with clothing, than an IWB holster under clothes.Also, and OWB holster is a lot easier to shift foreward or back slightly when needed for comfort to avoid the seatbelt latch when driving (or sitting in a chair/couch where the arm would press on it), then shifted back to the preferred position when not. Shifting an IWB holster just isnt as fast or easy IMHO.
That said, I carry either open, or "sloppily"/minimally concealed here in OR, so I dont need to worry about the little extar difficulty in avoiding the bulge that many OWB holster are more likely to give. I grant that IWB holster are a lot easier to use for when you really want to minimize the possibility of anyone knowing you are carrying though, and on the super rare occasion I want that, I do use an IWB holster with my small S&W m637. Otherwise, its the 1911 in an Uncle Mikes "duty" style retention holster OWB, or very occasionally the S&W in an old leather S&W OWB holster with retention strap.