Milt sparks or Mitch Rosen are my picks. Leather is much more comfortable than kydex for me and with a properly made holster and good belt I have no worries about the retention of the leather.
My favorite for AIWB is Tenicor. The molding they do on the back for the holster really makes it comfortable against your body.
My favorite hybrid for 4 o'clock is the Black Arch Protos. It is comfortable and breathable. Plus, they mold the kydex to wrap the trigger guard for positive retention.