I just got my hog island boa this week, and I'm already a huge fan... I'd definitely give hog island boas a consideration too. (Here are my pictures of her)
I don't have any experience with carpet pythons, but I've heard they can be almost impossible to handle when they are younger without getting bit fairly frequently (obviously it will vary snake to snake--but someone please correct me if I'm wrong on this).
I took a long time to decide between getting a hog island boa and a dumerils boa. I settled on hog island since the dumerils has the potential to get a bit bigger than my wife is comfortable withFrom what I've heard, you can't go wrong with either. I also stumbled on a few people commenting that their dumerils boa seems to go to the bathroom several times a week (urates only), which could mean a bit more work cleaning.