There are currently 161 valid species described, and dozens more discovered but not yet described/names having a "C" number for identification. With very few exceptions, all are identical in behaviours, care, etc. So it is really up to you. If your water is on the soft side, then the whole range is possible because the vast majority are wild caught. The few that are being commercially raised include Corydoras aeneus, C. paleatus, C. sterbai, C. panda, and probably a couple others. Nice as they are, I would avoid C. panda here, as this is one exception to the group in that it likes cooler and flowing water. Any of the others would be fine with gourami. Must have a sand substrate though. And some chunks of wood are appreciated. You could lay some dried leaves over parts of the sand; oak, beech, maple collected from a safe site are OK to use. Not essential, but again authentic so the fish like them.
Wild caught species appear in stores periodically, depending upon the collection times/seasons, but there are some very lovely patterned species worth the wait.