To be honest, I prefer to OC; but given how things have been lately, I do find myself carrying concealed more often just not to set off anyone. Not that I care, I just prefer to avoid the drama.
For concealed carry I go with a cheap and simple Uncle Mike's neoprene IWB. Carried that way for years, mostly a full-sized Springfield XD-45 but lately a XD-S for comfort, and never had an issue doing so.
Just remember if you're carrying in the small of the back to get the opposite holster (i.e. righthanded shooter should get a lefthanded holster) for easier draw!