I happen to like and own both but to answer your question, I believe FOR A BEGINNER, a Hogg Island Boa would be better, primarily based on maximum size of the snake.
There has been MANY posts similar to this one recently, and although you are simply asking for someones OPINION, so many people choose to jump on and argue about which is better and why and then show pictures and tell personal stories.
Again, I own both and can argue strong cases for both, but if you are looking for an opinion for a beginner, I believe the Hoggs would be best. They stay smaller and actually change color, as opposed to a Dumerils which can reach greater size, girth, and remains stable in color.
Thanks - take care
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'Tis not the stongest of the species that will eventually survive, nor the most intelligent, but the one most responsive to change' Charles Darwin
Thanks and take care - Joe Rollo