I would also choose the one on the right. The one on the left is less efficient, will use more fuel, and could affect smoke chamber temps since you are routing the heat and smoke through the warming box. I also have some concerns about your temps being even across the entire smoker due to the center mounted firebox when the flow is going to the right.
Good luck and can't wait to see what you build!
Good luck and can't wait to see what you build!