I have a lot of holsters for my XD 4in..40 cal, Crossbreed (now mounted to my headboard), Milt Sparks VM II, Galco Southern Comfort, Blackhawk Leather cutaway, Serpas (I have 4 of these), Desantis Speed Scabbard and Duel Carry II, etc...
My most comfortable IWB is without a doubt the Galco Kingtuk.