I own both a WSM and the Akorn. My recommendation would be the WSM; and the reason for me saying that is the control. If you look at the KamadoGuru forums about half the posts are either how to get the fire started without having a huge temperature spike or modifications that are needed in order to keep the temperature down. And some people won't like this, but I also think it makes better Q'.
The Akorn does have some positives like flexibility (high and low cooking capability), convenience (roll it in and out of the garage, hinged cover, and easier setup), and being insulated makes it more suited for a northern climate in the winter.
But if it's summer and it's a cook that critical because I'm doing it for someone else I grab the WSM.