I have both in Oxfords in 9.5UK. Alcudia works for me where Simpson is too tight. Alcudia has a higher instep and vamp and I think the way the shoe fits changes how it creases. My Simpson captoes crease right on top of my toes and make it tighter on my pinky toe. Both are narrow, but Alcudia fits my foot much better, more room across the forefoot, if only by a little bit.