I have an Uncle Mikes holster that I use for my XD9. I have also used a Blade tech for my XD9. They both work well for me. They have good retention, but also allow you to draw and fire quickly from them.
I have a Blade Tech for my XDM pistol that works pretty well.
I have a Fobus paddle holster for my XD9. I have a fair amount of range time on it (IDPA and classes) and would highly recommend them. I buy direct from them.