chiles

Does anyone know what type of pepper companies use for canned diced green chiles?  They are typically really mild. I am looking to grow, roast, and can my own this season and I am curious to see if anybody has some feedback on what I might try.  Ancho or anaheim perhaps?  We currently have 11 varieties of peppers started but I want to make sure I get the right type started before I run out of time.  Your comments are greatly appreciated.