I have mostly used IWB holsters over the many years I have carried a concealed handgun. I find that the IWB holsters conceal much better in all types of dress. The OWB may be more comfortable to many but I don't find a big difference. If one has a generous waist, then it may not be as comfortable. Also, if one has a large belly but tries to cover it or is in denial and deals with it by buying shorter trousers that are a few inches smaller than their actual waist size and suspends them below their gut, no belt holster works very well at concealment and particularly not a IWB holster.
My best advice is try them both. I have both for all of my CC guns. You will have to wear both for extended periods in various clothing types that you normally wear and under variable conditions to really know what you prefer. For the types of guns I carry most I have OWB, IWB, shoulder, ankle, pocket and fanny pack holsters and use them all at one time or another. Some more than others. Many would suggest that you carry the same gun in the same type of holster in the same location on your person to avoid confusion under stress. I can't argue against that...Good Luck