I have the WSM and I would personally get the Kamado Joe. I have enjoyed my WSM but the clean up sucks. The water pan is disgusting to clean out after every smoke, even though I line it with heavy duty aluminum foil it is still some clean up. It also does not hold temp like a Kamado and you are going to be burning way more coal. I have been using my Weber Kettle with a Pitmaster iQ hooked up to help control temp and it is better than the WSM.
If you have the money to make a lifetime grilling and smoking investment. Kamado Joe would be my call. Have mine for over 2 years now. Egg, Primo, Gill Dome are nice as well. KJ from the research I did was just a much better bang for the buck. It was 20% less expensive than the Egg for the same set up. KJ has a new larger cooker now which looks really nice.