Do you get along with your SO's ex?

My husband’s ex-wife is one of my favorite people in the world. I really like and respect her and my husband and I both trust her completely. As I was thinking about it this morning I realized the contrast between this and how we are forced to feel about my ex-husband. We literally have both ends of the spectrum. Now I am wondering which is more common, an ex-spouse who is a friend or one who is more of an arch-enemy. Care to share your experience?