When you consider how much pine they sell compared to the hardwoods, I think pine is the most popular.
I think I've seen a few poplar stave bows posted here over the years. I'm not so sure it's not possible. I'd start 2 1/4 inches wide, make it extra long, and back it before even starting on floor tillering. At least it's not terribly expensive wood.
Now for the pure speculation part of this post. Given: typically the more dense the wood within it's own species the better the bow from that wood. Maybe, along with choosing for grain orientation, you should consider the heft of the boards as you are meticulously disassembling some poor miminum wage lumberyard clerk's hard work of stacking.
As usual, if you are gonna spend the time on it, document your progress and post the pics!